1) I intend using a mountain bike for some DH, some trails in the mountains. what bike should i get. I would probably be doing more flat ground(mountain trains, bumpy ground biking etc, but also some occasional dh.
2)What is the difference between a Trail bike, a xc bike and a DH bike. And what bike would allow me to do all the types of mountain biking. EX: a bike that is good for everything?
For something like that you'll want to look at a full suspension bike with about 150 mm of travel for the front and rear. Enduro bikes are what you'll want to be looking at. Something like the GT Sensor or GT Force would be a good place to start.