If you doin't know the answer to those questions, the Palisades are NOT the place to figure them out. You'll hit at least 50 mph, maybe 60 (unless its a powder day).
In general, 1st you need to have very strong legs/thighs becasue your skis will be chattering and you'll have to hold things together. A fall at that speed WILL result in several violent head-over heel tumbles and can potentially be season (or more) ending.
You'll also want wide, stiff skis for stability through the crud that will innevitably be at the bottom.
Also, after straightlining the steepest top sections, I'd as soon as possible get a slight arc going (better stability with todays skis on a slight edge).
If you do it, do National chute 1st, then Main chute, then Box or Extra chutes. LAST on the list is the Chimney (if its even open). Don't run one that's closed because you'll almost certainly get busted by the patrol shack right next to it. Those busted for poaching the Palisades get a ride to the SHerriff's station and arrested, I've seen it happen.
Don't do it for the camera, make sure you're ready (and know you're comfortable at very high speed in crud). Be careful!