Hello Tori,
welcome to MR. Hope you feel at home here.

The PB 360 is a definitely good choice for a first reading device.
1) You can read PDF and ePub with or without DRM. Additionally you can read PRC, HTML, TXT, DOC, RTF to name a few (all without DRM).
2) I'm not sure if I understand you correctly. The battery of the PB is a Li-Polymer battery which should last for the next few years to come. Even then it should be rather easy to be replaced.
3) Depends on where you live since most shops have geographic restrictions to some of their eBooks. Also depends on what you read. Fictionwise is a good starting point, Kobobooks too. But that's just two examples.
Definitely not Amazon since they don't sell ePub and use a format no other reading device can read easily.
4) In the European version a charger is included. Should be the same for the US version. So you shouldn't need to buy one. If there isn't, buy a USB adapter.
Avoid using chargers of other electronic devices in general; they may work, but there's neither guarantee nor warranty if anthing should happen.
5) Nope, you can use any kind of microSD card
6) At least 16 GB (not sure if the PB 360 already supports 32 GB)
7) That's a tough one since there isn't any official accessory besides the leather pouch. So you'd have to find your own solution or browse through this forum if anyone came up with an idea.
8) Not as far as I know (mine had some Russian eBooks, but that's slightly off topic

). But there are indeed so many free eBooks around. First, start here at MR in
this thread, next, there's
Project Gutenberg, but also sites like
feedbooks,
manybooks,
smashwords, ...
9) The white (ivory) one indeed is more comforting to the eyes. For a lot of users the black border is too solid a frame which "limits" the dimensions of the screen while the white case rather "broadens" the screen.
Hope this is of some help.