turning/ body position

In a corner, sit up near the tank. When i go in i sit on the tank and lean back a little bit, does anybody else lean back?

it depends on the type of turn. Say it was a 180 degree burmless corner. the best way to do it would be to sit up on the tank keep inside leg out and streched for better balance and gradualy roll on the throttle. It also helps if you know how to "lay the bike down" in a corner. Say you had a corner with a burm. if you were to go on the inside of the corner you would probably have to "square up" the turn while holding the clutch and reving your bike, then release the clutch. i don't have much experience there so you would have to experiment on your own with that one.

As you start getting faster through the bermed corners you will want to lean your body into it more, thus keeping all of the weight over the tires. The reason it feels better right now to keep your shoulders parallel to the ground is that you aren't properly utilizing the centrifugal force either due to your speed or your position in the berm. As you're entering the corner use your front brake to slow you down to an acceptable speed and help you sit higher on the tank. The higher the better, and stick your leg straight out to the front and slightly above the ground as headshot was saying. You should be getting on the gas as fast as possible during the exit. Corner speed is the most important thing about track riding.

You are right to push the bike down lower than your body. Use that position to put weight on the outside peg. Berm or no berm, the greater the downward force the better your traction will be. What really limits how much lower you can get the bike than your body is that your inside leg will hit the ground if you try to go too far. Notice the body position of someone who knows what they're doing:

http://themxtrack.com/BillyTurn.jpg