According to IPS's migration tool, VB 4.x supports 301 redirects during the migration process.

My questions are:

1) Are these for the "friendly" URL's I'm currently using or just the basic vBulletin URL structure that I'm not using (IOW, is it going to only 301 redirect links that I don't even use?)

2) Do I need to set/develop my new IPS FURL structure before or after migration?

These questions would be answered better by the customer support itselfs bescause the Importer and the redirection rules are made by IPS themselves. This is the User2User help section.