Let's see.... wish I could be more help.
1. - Not without some hacking. Haven't seen a hack for required fields on registration yet.... but it's possible.
2. - Each user will follow the time offset you've set in the theme file
until they customize it themselves in their preferences.
3. - URL to mail is done through PHP... it uses how the php.ini is setup to do mail. So there are no settings in threads you need to fool with.

4. - Subforums are not available... but you can put forums under categories.
5. - The instructions with
this post should help you remove the ratings.

6. - Logo: From your admin menu, edit the Generic Header. Put your Logo (and needed HTML in there) it will appear on every page. Different logo per stylesheet... not really. Some have experimented with using a table cell background image in a stylesheet to accomplish this... but I haven't tried it.
Hope that helps.
