Streamline site setup and function

I’ve just installed WP mu to see how it might work. Let us suppose I want to have 1000 sub sites from various individuals. However, I can’t really expect them to be WP users and understand Dashboards, plugins etc etc. So… how can I set up this network where:

a. new site owner registers and they get their site (easy part)
b. the get transferred to a welcome page on their site
c. they have no access to Dashboard to fiddle with the backend stuff.
d. they can post, of course, use existing categories and tags etc

Prob. more but that will do for now. Any ideas much appreciated.