Yes especially online modding.
You get banned for modding anything dealing with an Xbox
I wouldn't recommend it. Bungie have an automated program that checks all activity online and you can be punished by having your account banned from matchmaking, have a full credit/armour reset or in extreme circumstances you can be banned from xbox live.
you get banned from Xbox Live. If you do ever get banned its because of glitching modding. Since I'm a glitcher, i have to be careful of what i do for my glitching have never gotten banned, but i think Bungie found out what i did and now i cant do any SHOOTIN AND LOOTIN achievement's on campaign
Yes.
Yes, but you will get hardcore banned!
Yes
Yes but it is against rules, and you may be banned from Halo and even your own xBox.
If you want to be banned from your Xbox console permanently eg you cant ever play on it again, then don't try to do it!
There are ways to mod, and if you mod forgeable maps you will not get banned. Modding online will get you banned from Halo: Reach, and it is normally permanently depending on the severity. People also mod on J-Tag Xbox consoles, which completely modifies the game, however you cannot go online.
Modding is illegal and you will get banned from Xbox permanently if caught.
I take it you mean the GPD file for modding. The name of the Halo: Reach .GPD file is 4D53085B.gpd Message me over Xbox LIVE if you want a modded GPD file. GT: The 3rd Arc
you can get un banned without getting another xbox just ether wait the ban out or get a new account and don't mod so you wont get banded again