1. Assuming I've backed-up my old board, can I delete all of the files except the two ultimatebb.{php,cgi} redirector files?

2. What is the functional difference between redirect types 301 (Permanent), and 302 (Temporary). I.e., when would I choose one over the other?

1) I haven't yet, but from I read here it's perfectly safe to delete all the Classic files -- because you're not using them anymore if you have the redirects in place. I haven't yet because 1) I want to retain access to it to help with customer support here if I can, and 2) cuz I'm chicken.

2) From Google's stand point, from what I understand of it, is that a temporary redirect will keep your old content in their index while also indexing your new content. It's probably a good idea to start off that way. After a while, after your old content is long gone, you can switch to a permanent redirect and your old content will slowly be removed from the search engine databases.

My response is from my current understanding. If you want to wait for a second opinion, I won't blame you.

If you've backed up and upgraded, you should be able to purge; myself i just did that ;).

I would recommend a temporary redirect for several months, as it'd give SE's the chance to locate new content; then update to a permanent redirect. Myself I went this route and left it as a temporary redirect for 8 months.

Theres a large debate over 301 vs 302, so that's just a sugguestion from me.

Very good guys, thank you