Wow, thanks for such a fast reply. I actually bought (apologies if this is bad) one off of eBay that, from what I could tell, was wrapped and in solid working order (battery wonkiness aside). That said, these suggestions make me feel a lot more confident I can clear this up.

((Edit to avoid a double-post: I've been reading about adding repos to my N900 (I wanted to get DropN900 for Dropbox support), and is it okay to enabled Extra-Testing and/or Extra-Devel... or what should be proper protocol to not screw myself by doing it (looks like the kernel might be in Extra-Testing)?))