the only way i know is to delete the entire game save file which will also remove your multiplayer forge and spartan ops progress.
its in system settings somewhere to do with game saves
Everything in Halo 4 as of now is co-op. Campaign, Spartan - Ops, and Infinity (Multiplayer) Internet, local, and system link.
yes
Only in Online Campaign, Not Local Play
Yes
Yes but only if you beat Halo 4's campaign on Legendary. I suggest co-op. That's the easiest
No, Halo Reach occurs much before Halo 4. In the timeline of the actual world, the games go: Halo Wars Halo: Reach Halo Combat Evolved (And Anniversary) Halo 2 Halo 3 Halo 3 ODST (Same time as Halo 3) Halo 4
Both players will be Master Chief.
you cannot, only 2 are allowed
No it dosent
Most likely in Forge, Custom games and Matchmaking. Campaign? NO
Halo 3 does work on Campaign as well as Xbox Live with up to 4 people
You and a friend IRL or over XBOX Live work through the Halo : Reach campaign missions