Choosing a decent 12 string guitar

I stumbled accross a youtube video of zakk wylde playing a 12 string for one of his live performances for the book of shadows CD - and he's using a 12 string and pulls bends and all. So I'm thinking of getting one -


Is there anything I should know before hand,
such as ...
limitations of a 12 string, t
the ungodly cost of replacing strings?
Tunning? (I know we have one set tuned to E and the other to Eb),
brands to consider
steel string or nylon (if they exist)

or any general advice ...

Here's the vid if any of you guys are curious
http://www.youtube.com/watch?v=6OOrWqIzgxU