I'm building a new bathroom. I have one drain pipe 6" going down into the ground from the bathroom floor. It sticks up about 8" above the floor right now. I want to run the water drains, shower drains, and toilet all into this one big pipe. Can I do this, and how do I run the pipes with air breather pipes so it doesn't stink and all runs smooth.The tiolet will be built up on a pedelstal, as will the bathtub.

By "air breather pipes" I'm assuming you mean the ventilation stacks? Are you trying to run all this into the one pipe because you want to avoid having to drill more holes in the floor? It sounds to me like your question has a lot to do with your local code. I would definitely contact your county or a proffessional depending on how much experience you have with piping.