Welcome to InternetTabletTalk and the N800. You've certainly got a great tool, and you can do nearly anything you can think of (related to the internet) with it.

I'll answer what I can and let others fill in the blanks:

1. I don't use Pidgin so I can't help you. A future update (it's currently available as somewhat of a hack) will include native support for all of the IM clients (MSN, AIM, etc)

2. Again, not sure. I don't know that I've filled mine up yet, but certainly keep us posted.

3. As long as you have OS2008 installed, you've got A2DP support built-in. To check the OS version, you can go to Settings - Control Panel - About and it'll let you know what version. The latest is OS2008 50-2. You can go to http://www.nokiahowto.com/A4410958 to learn how to update with Windows or Linux.

4. I have the iGo and it's completely phenomenal. There's tons of hotkeys, and you can customise these through the Internet Tablet's control panel. Amazon has them for under $100 (I got mine for $30, but the last I saw on Amazon it was up to $60, still a great deal). The key spacing is the same as a laptop keyboard, so it's very comfortable.

5. The N800 camera just pops in and out, couldn't you keep it popped in, or do they do thorough inspections? I would imagine you could do some sort of surgery to disable the pop-out feature, and therefore disable it.

Congrats on your new find. You should definitely explore the Tableteer site, there's some links to great software on there, and you've found a great resource here.