Welcome to the AA side. You would do well to take a look at the FAQ at the top of the page

http://www.flyertalk.com/forum/ameri...check-out.html

Specifically, post #2 has links to quite a bit of discussion about AA elite status. This will answer a number of your questions, plus some you didn't know you had.

The wiki also includes extensive discussions of the AA seating options.

You may also want to look at these threads:

http://www.flyertalk.com/forum/ameri...co-better.html
http://www.flyertalk.com/forum/ameri...-hello-aa.html

(Search terms {"AA" "CO"})

Cheers.