yes it can(and mostly will)take weeks to complete a game(you could start with higher tech levels or a small sized map, etc to shorten it), but that's not the point: it's just more fun to play against humans...the AI can always be beaten
if you find some players who agree to do the first, say 40-50 turns within a week, you're on the lucky side. as your empire grows you'll need more time and it's not that bad if you do only 1 or 2 turns a day!
simultanous movement is the best option for playing PBEM games, for several reasons:
The host of the game gets all palyer files and will send them back. so if the host is reliable the game will proceed quickly(if one player takes to long to mail the file to the host the AI could take that players place(just for that turn))
in a turn based game player A would mail his turn to B etc 'till the file returns to A....so if one of the players take aeons to go on, all must wait
Look here :
http://www.shrapnelgames.com/ubb/For...ML/000003.html
there are other sites out there where you can find PBEM players...check out the links at the MM homepage!
hope that helps