No there is not a mod
Yes you can drive a Hornet and a Banshee. You can fly a Pelican and a Phantom if you find the right glitch, easter egg, or mod. But I dont approve of mods.
There are some glitches that you can exploit in halo 3, like super destructive weapons in forge and no text in halo main menu. However, for more common mods like actually driving the scarab or piloting the pelican/phantom, you have to have a dev mod. You can get that developers kit from Microsoft or Bungie.
unfortunately without mods, it cannot be unlocked :L
No, i have tried to find many different ways, but it is not possibble. people with mods possibly can, but otherwise, no
You can't. :< Edit: I don't know if you can in halo 1 or 2, but you can on halo 3, it is possible without mods and is really a glitch, it is tricky however, guides to do so are on youtube.
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/
Mods.... search halo armour oblivion
You can in HALO 1 if you use mods, but it has to be on the computer.
As of now the Halo: Reach beta is gone, your not going to be able to.
well theres cliff mod rocket mod fishy mod night blood gultch mod jerrassic park mod sniper mod no gun mod spiner mod bumper cars elite mod pelican mod echo 116 and more i dont know because you can make your own mods
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.