If you stay with tubes, you MUST run screws otherwise a little movement will rip the stem out. But I've seem most run without, which saves weight. The tire will move a bit, especially during the first few passes. I rotate them side-to-side, mainly for wear.
It seems most racers use 9" slicks on a 10" rim. But I've heard of pressures anywhere from 14 to 26 lbs with no pattern that I've noticed relative to weight. I ran 22lbs in bias ply tires and now 20 in radials weighing 3,530+.
Locomotion Racing
http://www.geocities.com/locomotionracing