They added a check that identifies impossible combinations of weapons. While the game has a wide range of random drops, there are things that can't happen during normal play. Hyperion weapons with Dahl parts, Quality 5 weapons in the hands of Lv1 players, etc. The check eliminates any weapon that could not be normally found.
go to the gun shop at the bottom there should be gun mods. i think
....You can't so either tell them to take off the Mod or just play with someone else.
No, unless the modders themselves have put a price on it.
You are not able to at all without the use of mods.
No, what they did was patch the game so that 'impossible' weapon combos added by mods, are removed. You can mod in a weapon that 'can' exist as far as the random drops tables are concerned, and that weapon can be duped.
Mods (modifications) are free. You do not need to pay, however, you do need to be able to download them. Use Magic Launcher or Forge to do this.
As of now the Halo: Reach beta is gone, your not going to be able to.
Yes, you can install as many mods as you want as long as they are compatible with each other. Some mods use the same .class files which basically means they aren't compatible. You will know if two mods are compatible with each other because your game will give you a black screen and you won't be able to play until the mods are deleted.
There are definitely mods for that, like moreores, for Bukkit.
Yes, you're able to run multiple mods at once. Although this may cause a but of lag, and would be recommended for newer/higher RAM capacity.
COD WAW has to be my favorite, just because of the zombies and there is plenty of mods to use. A few more are, Dead Island (Any One), LittleBigPlanet, Payday, Borderlands, and Left 4 Dead.
no but there might be mods where you might be able too maybe halo reach will let you