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. 
