Transition (migration) to new URL and help with existing redirects

Hi,

I’ve read a number of posts and instructions regarding transitions to new servers, URLs, etc. but haven’t quite found a solid answer. Any help would be appreciated.

This is the situation:

existingsite.com is fully setup with WordPress on a Site5 server. newsite.com has been registered and is currently redirected to existingsite.com. What we’d like to do is re-brand as newsite.com and move everything over. The server is the same, only the URL is different.

How do I:

a. Transfer everything to the new URL – WP files, database, etc or do I actually need to move anything?

b. How do I deal with existing redirects (using redirects plugin) which, after the transition, will need to be re-redirected to the new URL?

On a final note, are there any other considerations I should be aware of? I’ve obviously registered the site with Analytics, Web Master Tools, etc.

Thanks for the help.