SW, after reading all the responses, I believe you've got it covered.
Keep the butt as far back as possible on the downhills while feathering BOTH brakes in the lowest gear you're comfortable with.
ALWAYS weight the outside peg in turns. This helps to bring your body's centerline more closely to the machine's, helping keep traction. The same will apply on off-camber trails.
Most important is to stand as much as possible while keeping your weight centered on the bike, and LOOK AHEAD! Look where you want to go, and not at the tree you're about to hit!
This pic was taken of me jumping into a 5 foot deep creek bed loaded with rocks....3rd gear, wide open.
