Would I be able to trade 1or 2 games in for another, Say Halo 3 and Halo 4 for one of the Fallout Game's that run on Xbox 360.

All games have a value. At this time we have many copies of Halo 3 & 4 and their value is quite low. Currently Fallout 3 & New Vegas are under $10 each at this time. You would have some trade value in your games, but it would not be a even swap. Hope that helps.

Trade in value is always low, better to trade with friends or sell it on your own. Otherwise, yes, you can trade games for credit towards another purchase be it games , controller s etc.

Actually yes thank you