Well, the 5th question was the only one that I could really answer.
For the rest:
1) notes on the margins of a pdf
I didn't see any information on it, but I'm not sure that I would want it. I think that for reading a pdf, the best thing would be to remove all margins. As for writing, I don't think that I would be able to write as small as to fit that space. I mean I haven't seen anyone demonstrate small writing. The demonstration on note-taking on the 302 can be found
here at 1:35.
2)discounts for academics
I have never seen it discussed, so PocketGoods is probably the only one who can answer that.
3)on language
I remember reading a post where someone asked about what happens if the reader comes in cyrillic, and I remember that the answer was that you can easily change the language, since "language" will always be in english so anybody can find it. I just can't find that post.
4)on browsing
You can see a demonstration of browsing with the 302
here, again at 1:35. So we know that they can do it with the older model on wifi. I'm not sure what the limits with 3G are.