- What limitations does WPMU have compared to the normal WP?
No theme editing, and no access to the server for things like uploading new plugins. Sometimes it's billed as WP-Lite.
- When WP releases a patch, does the WPMU patch come at the same time? Or how soon after?
It depends. Sometimes it;s right away, sometimes not.
- Do all plug-ins designed for WP work for WPMU as well? If not, approx. what % do not?
Not, because of db structure for user blogs. Hard to say what percentage, but most will work, many with only a slight change. Very few I've come across bomb spectacularily.
- Anyone know how WPMU's blog farming capabilities compared to MT's blog farmng capabilities?
Better? :D I'm not quite sure what you're getting at, but I found it much easier to have multiple blogs with MU than I did with MT. *shivers*
- Did I read it correctly on the front page that one WPMU user cannot have access to multiple blogs? What about admins?
Site admins have all access to all blogs. There's the default admin on setup, but you can add another user as an admin. Each blog admin can admin only their blog, but can easily be added as a user to another's blog.
- Any surprises I'm going to experience being a WP user moving to WPMU?
How messy you'll get mucking around in code. :) install is different, please read the instructions - it's not quite the same as installing WP. The above-mentioned theme & plugin thingy. The one thing I still have trouble getting used to is as an admin, if I need to edit a theme for all, I have to do it on the server, whereas in WP I'm used to using the backend editor. (actually, now I'm more use dto going in the back-end...)
MU is just a little more hardcore as you're dealing more with server & DNS issues.