A) Gameplay/Game types
1. What is the betrayal/booting system? How does it work?
Dont Know
2. Can you turn off join in progress?
Don't think so.
3. Is 343 going to add new game types soon or at any point? Such as doubles, etc.
Yes not sure when but they've showed off gameplay of SWAT and Grifball. so others are very likely.
4. What is that 3D box emblem in the HUD right above the armor ability you're using?
Its your progress towards the next ordinance drop. as you get points for playing it fills up and you get ordinance.
Weapons
2. What's the difference between a Battle Riffle and a DMR?
DMR is single shot and with a longer range. BR is a three round burst.