A mod, or modification, is a way to change the game you're playing into usually an unintended use. In halo if you mod on an online game you will be immediately banned because modding is a fancy word for noobing. So don't do it
depends on what you're looking for. but most good mods in halo require a jtag. but a good site to look up mods is- http://www.thetechgame.com/
As of now the Halo: Reach beta is gone, your not going to be able to.
Mods.... search halo armour oblivion
You can in HALO 1 if you use mods, but it has to be on the computer.
Yes. There are a lot of mods for Halo and Halo Trail on PC.
See halomaps.org for mods like sonic for halo. It is only for Halo Custom Edition, but you can convert it to Trial or Retail with Pearl or Demo with Queene Anne's Revenge.
Yes
Go to www.MacGamingMods.com it will be There
No, not without mods.
Not without using mods.
Aimbots do not exist for Halo 3. There are mods for maps though. If you put mods on your file share, it is possible you will be banned though.
There are no cheats for halo 3 there are only mods and hacks