Welcome oly... let me try to answer your questions with some links to threads discussing these issues:
Snow tires:
http://www.e90post.com/forums/showthread.php?t=631
E90 AWD - production starts September, can order now:
http://www.e90post.com/forums/showthread.php?t=293
Flat/punctured run-flat tire:
http://www.e90post.com/forums/showthread.php?t=1229
Gas Mileage:
http://www.e90post.com/forums/showthread.php?t=1252
Break-in:
http://www.e90post.com/forums/showthread.php?t=1237
If you don't mind doing a little bit of reading there's tons of info in those threads... and if you have anymore specific questions, feel free to ask here or in those threads
