Lol advertising in threads..
Anyway, I can answer only a few of the questions you asked. Hope it helps.
1) I don't think running "3D" would affect the battery life. It should still be the same.
2) This link has a picture of an Ax with a 1800mAh battery. The 2200mAh one should be slightly thicker.
http://www.aximsite.com/articles/link.php?id=306
3) I think you should start a thread under the GPS section or have a look at that section of the forum.. Should be able to answer your question.
4) Yes there is, but as mitodna said, it is very costly. Might as well get a camera that uses either SD or CF and justs plug the memory card into your Ax after you take the picture. Better resolution too. I'm doing that at the moment.
5) If you're going to buy off Dell then I don't think there is anything to worry about. The latest released ROM is A06 but there are a few people on this website that has recieved Axes with A08. Just read around and upgrade it to the latest ROM when you recieve it.
6) Fast and decent SD card. Most SD cards are decent, but you might try brands like Sandisk, Kingston, A-Data(?), etc.
Oh and don't forget to apply the fake server patch when you recieve your Ax. It fixes most problems if you have not already read about it. Here's the link.
http://www.aximsite.com/boards/showthread.php?t=112638