Is there a way to backup all the apps that I've purchased/downloaded or would I be able to re-install them? That is, would the Market know about what I've bought (like Appworld from RIM does)?
market will know what you bought (as in paid for) the free apps you downloaded are a crapshoot with market remembering or not. i think it's much better at doing that in 2.2
you can backup your apps with something like Titanium Backup or sync them with appbrain as well