Oh, by the way, I almost forgot the most important part ... and I hate to do this but I must ... NO BANNING, NO BANNING, NO BANNING! If you must ban somebody then ban those who really cheat with the use of evil controllers, lag switches and such.
Quitters and AFK's are not cheaters ... just quitters. Idle boostring can be done away with by giving credits based on kills/score ... no kills - no credits. 100 - 200 credits a kill seems about right to me. Certain kills could be rewarded more than others depending on difficulty or rank of player killed etc.
As much as I like the Halo franchise, and I have all the games, I will not buy Halo 4 if it includes any type of banning of quitters/afk's.