Welcome to MobileRead, f00l!
How I miss good ol' Half Price Books.

One of the several things I do miss about Texas. Texas
proper that is: life here at the Embassy does have its privations.
You sound like you're in a good position to wait, actually. Usually my advice is to decide whether getting the "next" set of new features is worth the cost of not having the use of the device is in the meantime ... actually that's my advice in your situation too, it's just that the answer in your case is probably different from what it would be in most cases.
One note on the Kindle, the wireless (EVDO) function
can be turned off when it's not in use so you can, nominally, get about a week's worth of use out of the battery, mileage will vary, of course.
Regarding the Kindle format, it's just a variant on the Mobipocket format. Since you asked the question: it's one of the very few formats which
haven't really been hacked yet. Given its popularity, that's actually fairly impressive. It's also a testimony to the aggressiveness of Mobipocket's legal team.

Lately, though, the hacking efforts have been aimed at allowing reading of "regular" (as opposed to Kindle) secure Mobi files on the Kindle, not getting stuff
out of either format variant.
Anyway, we're glad that you decided to join us.

Pull up a chair and make yourself to home.