For my 50th birthday (a long time ago) I went to Buck Baker's Nascar Driving School. They taught hand position 10 and 2.
However, with the three spoke wheel in the cars I've had, I'm more comfortable at 3 and 9, and there are thumb notches in the horizontal spokes which facilitate that position.
As far as how many hands on the wheel...both hands ALWAYS on the wheel...aside from the brief removal of right hand to shift.