OK, here goes....
1. Yes, definitely - though you could say that this depends on what texts we are talking about: some 'popular' philosophy can be quite jargon-ridden, and some 'academic' philosophy can be remarkably free of it. However, in general, yes.
2. Well, once again, that depends on the profession - it's difficult to generalise. Law, for instance, is more jargon based, but some might saw necessarily so (hmm...). But manual professions can be riddled with jargon also - building or plumbing! So, this question is difficult to answer fairly. However, I certainly think that SOME academic philosophy is unnecessarily obscure in its terminology.
3. Well, there are pros and cons for both. Generally, popular philosophy is trying to reach a wider audience (and earn money for the author...ahem!), whereas academic philosophy is trying to further the boundaries of knowledge (or impress peers and perhaps get tenure...ahem!). So, given that these purposes are separate (mostly) it's difficult to say which is better - it's like asking, "Is Jim a better guitarist than Tracy is a daughter?" Well, they're not measured on the same scale, are they? "Efficiency" will differ according to context. However, I do think, in general, that academic philosophy tends to suffer from what I call "power jargon" - i.e. needlessly obscure terminology that is aimed at impressing others not being clear.
4. Sometimes yes, sometimes no. However, even in really complex debates, jargon doesn't always help. It is the ideas that are difficult to grasp, and whilst we need some terms, I think things can often be simplified - but often aren't!
5. Well, this is a problem occasionally. For instance, words like "self" and "mind" can have very different meanings in philosophy and everyday usage. That is why philosophers need to define terms, of course. However, the fact that a common word can be confused with its technical use, and vice versa, is a reason TO HAVE jargon in the first place! If I say "socially constructed thought complex" instead of "self" then no one will get confused! Well...
6. Sometimes. There are good examples of popular philosophy and bad, and the same for academia.
7. No, not in general. Some philosophers will perhaps answer yes to this, but those will be the ones who take themselves too seriously, I think. On the whole, popular philosophy does no more harm than popular genetics books, or popular books on psychology, science, whatever. The truth is that popular accounts are meant to demystify and - well, popularise! If ideas were never popular, then they would never affect society on a broad scale. Darwin's ideas are popular and change the way people think about things - who we are, whether it is necessary to believe in God, etc. - but without people necessarily understanding them fully or technically - in fact, with a number of misunderstandings! Is this a bad thing? Occasionally, but I think it's probably better that the ideas are out there in some form, for at least then the misconceptions can be addressed. Someone who had got hold of the wrong end of the stick about Nietzsche, for example - which is quite a lot of people, still (he was a Nazi, anti-semite, etc.) may therefore be more interested in getting a better grip.
8. Yes. Almost by definition. I certainly don't think that Blackburn, etc. can be considered "dumbing down" - Blackburn is an excellent writer.
9. Yes.
10. PhD.
Hope all that helps.
