I definitely do NOT mean to imply rational proof, merely that certain possibilities are rational options. So, in some cases, there may be insufficient proof to claim conclusively that something is the case, but equally their rational possibility is not ruled out.
Agreed. I wouldn't want to imply proof either or 100% accuracy of my atheism. I would say that I have a lot of sympathy for a deistic perspective at times, but as you later point out this is kind of pointless. I would want to say things of this deity, attribute characteristics to it and then I'm in the realm of theism. I'm no expert on this, but have tried to read the Bible, Lewis, watch preaching on Youtube, and a ton of wonderful debates. I'm impressed by the ardour of the theists and how badly they want the world to mean something other than itself, but not by their ideas or arguments. On a scale of possibility or probability thesists would barely get beyond improbable (ancient texts and dubious history are not compelling), deists a bit beyond improbable (abstract arguments can be compelling) and the atheist case would be the most probable.
By (2) I simply mean that I am interested in religious traditions, accounts, metaphysical systems, etc.
I’m not sure how you can equate interest with (2) faith (unless you meant to type 1 and not 2 at that spot). I’m in total harmony with you there, having interest, but this interest, though it may lead to faith is very far from it, and in my case being open to learning about and interested in religions is completely tied up with atheism!
their stature and sincerity is a swaying factor.
It can be, but this goes both ways, people on both sides can have stature and be sincere, so there's a problem with this kind of pro hominem in that it doesn't really get you anywhere.
So, you need experience. This doesn't need to be supernatural or revelatory - though it can be - but merely to suggest that materialistic atheism is not the whole picture.
I appreciate your appeal to experience. Spinoza is delightfully referred to as “the god intoxicated man” and I think most of us have felt this intoxication. A great recent, relatable, and very public example is Francis Collins' story of his conversion in his book The language of God: how he had wrestled with the problem, until one day while biking he saw some wonderful sight, a waterfall split into 3 streams and the beauty or awe was enough to get him down onto his knees submitting himself to Jesus Christ.
“It might be a physical sensation, a coincidence, a strange dream”. This is the believer’s point of departure from me. From these meager material facts (feel free to slaughter me here – obviously these things are all mental as they are experienced and I don’t have a sword to wield against dualists or idealists yet… though perhaps I’ll become one

to the leap to non material or supernatural realities.
James inveighs against “medical materialism”, that because my belief could always be said to caused by some state of my mind and/or body, this invalidates the truthiness of my claim. I can see this. One might be completely depressed or elated and have one's thoughts coloured by this and come up with a variety of ideas and it would be absurd to say that because one was down or up that the idea couldn’t be true. On the other hand given the causative, hell constitutive role of chemistry in some mental states, especially the ones we would call numinous or spiritual, visionary, etc. I have a problem with trusting what can be brought about by drugs (LSD, mescaline), or stress or schizophrenia. Huxley interestingly points out in Doors of Perception that back in the good old days we were walking around half starved and nutritionally depleted, that this itself could lead to interesting mental experiences, and that on top of that some people would be flagellating or otherwise harming themselves and possibly heightening the visionary effect.
So cautious skeptic that I can be, I’m not sure that even in these inspired moments that we have gotten beyond the body and materialism. Not only that, but experience itself is neutral in a way between theism and atheism. While we can speak of those inspired moments when we experience some taste of cosmic significance, there are a host of experiences that would point one the other way, things irreconcilable with the popular ideas of God as Just or Loving or Perfect: seeing your family slaughtered in front of you or being locked in a basement by your sexually abusive father for decades.
So with that rambling, on to your Thomistic flavoured 5 ways

1. This is an interesting point and one that needs a lot of elaborating. What about the similarities do you find most salient? I do have a copy of Perennial Philosophy which I used to adore and will have to pull down. The differences are something that atheists and theists use. I would point to the stultifying confusion wrought: God is personal or impersonal? One or Many? Loving or Wrathful? Christ or not? In the world or not?
Some theists (e.g. Tim Keller) will point to the differences as a reason why you shouldn’t go in for religious pluralism, something along the lines of “we’re not saying the same things: as a matter of fact they’re wrong, and there’s quite a heavy price to pay for this as my guy says the only way to get to his father is through him”.
The similarities here might be due to the other similarities among human cultures: families, morals, art, etc. that (and this is horribly truncated I know) they are part of what it is to be human. Interestingly even though I don’t believe in a God, I don’t have the choice to be ignorant of the idea or not have an opinion on it. I don't know where the idea originates or what its future is, but it has taken hold and is part of us in some way.
2. This is really interesting! For me the idea of God is kind of pointless, because what am I supposed to do? How do I know what God wants of me? Which church should I join? We all seem to be stocked with violent impulses – should we act on them? Should we live compulsively or with control?
You’ve got a pragmatic role for God and I can see conceding an uppercase Pointlessness: to existence or life as a whole if there’s no God, perhaps like athletes playing before no crowd, but once you get to the messy details of life – I have no idea what God wants.
What are Wordsworthian physics?
3. There’s a tension here I think between your idea that “God thinks we’re ants” and the idea that we can have direct communication. Maybe he’s just messing with us?
4. I’d love to hear some of these possibilities. I don’t have anything original to add here, but for me this is a very strong argument: Sam Harris is talking to Deepak Chopra (Youtube is filled with debates and panel discussions – it really is amazing) about consciousness. He says something like: consciousness is very delicate and that by damaging parts of the brain you can cause major and irreversible changes to consciousness. So here’s the question – if parts of conscious experience can be so violated by small changes or damage to the brain, how plausible is a claim for consciousness to survive unscathed the death of the entire brain? Not very. What do you think?
5. Again you need to elaborate on this – the personal experience admission is intriguing. I have some pain issues and sat through the first of a 12 class series on meditation with the specific aim of getting your Chi up. It was four hours long and not in my first language, but I got the gist of it. He said the key was to focus on feeling your sternum getting warmer. Later you would learn how to channel the Chi up over your head, down your spine then around your rectum and back up past your stomach. The interesting thing was that he was very, very concerned to mention that he had a degree in physiology, and that there was a study done with hospital patients in China that showed improvements in their disease. Part of his presentation involved a discussion of how energy is produced (if that’s the right word) in cells. There was no linkage to the Chi concept and I think that it was simply an attempt to positively blind with science. I didn’t go back (for a few reasons). I think “Chi” lacks explanatory power because there is no way to distinguish between different theories of Chi- they could all 'work' and never be shown to be wrong (perhaps there are some Chi experts to show me up?), like when Penn and Teller get two Feng Shui experts to do a session on a house and they completely contradict each other.
If there is some kind of subtle energy how do we know it’s there? What would the difference be if it wasn’t there? What does it do? What doesn’t it do?
There’s another tension here too. We have a great deal of respect for individuality. We all know what it’s like to know something or feel something, but not be able to get the words out or express it completely (or at all sometimes!) . So we would like to give individual claims to truth or to profound experience some kind of credence. On the other hand we have pejorative sayings like “well that’s just true for you”, “that’s just your opinion” or the kind of desperate (perhaps that’s unfair) “well it’s true for me!” or “that’s just how I see it”. And while I want to respect someone else’s experience as long as it isn’t causing them to harm themselves or other people, I have a skeptical block when it comes to certain kinds of claims or actions, like Francis Collins above. What role can personal experience play? How do we decide between completely contradictory interpretations of personal experiences? Collins sees the waterfall and the trinity erupts out of it and envelops him. I see it and think "wow, that's beautiful... wait, oh, a bird just picked a fish out of the river above and is eating it alive... that's kind of horrible".
In the end I have to say that the possibilities, or probabilities are not equal, and though this post is a poor apology for it, much closer to atheism.
If you’ve made it this far, thanks. Hope that made sense, and that it’s length (and hopefully some depth) served as a kind of penance for it’s great lateness. In my defence, it was a rough year!