Would really high final approaches also help? I spent several tanks on both the TH .40 and the Mach II pulling very high approaches and cutting back to idle. I'd come down steep and kill speed by leveling out very close to the ground.

What do you mean by high speed rolls? Do you mean being able to handle orientation with the plane rotating quickly or do you mean being able to handle the high speed and throwing in rudder/aileron to keep the roll straight?

The most I can do right now with rolls is yank the stick over hard and wiggle the elevator from up to down. I've yet to start adding rudder to my rolls, as just my elevator wiggle is still pretty jerky. I'll often get a very sloppy roll that has a bump in the middle where I accidentally threw in too much down elevator.