I'll attempt to answer as many as I can. Don't have my Kindle yet, but I did a heap of research beforehand.
3. What is the actual storage size on the Kindle 3?
4gb, 3gb accessible to the user.
4. Does it really have a 30 day battery life? Or is that an inflated number?
Inflated but depends on your wireless usage and how much you read obviously.
6. What formats, exactly, will the Kindle 3 recognize?
AZW (Amazon's format), Mobi, TXT, PDF. Calibre will convert other formats to Kindle supported ones though. Amazon has an email service to convert Microsoft .doc files and HTML.
7. Does only the PDF format allow landscape, or do other formats as well?
Yes, landscape can be used in other formats.
9. What, if any, hacks are available for the Kindle 3? (kind of like rooting the Nook)
A jailbreak was just released which allows hacks from previous gen Kindles to work. Right now, I think it includes Screensaver hack, fonts, dictionaries. There should be more in the days to come.