I can tell you the answer to number 2, because it's the easiest.
Pitch Diameter equals 9.55"
Method: Pitch of worm gear (ie distance between threads on worm) = 3/4"
For a single thread worm gear, for each rotation of the worm, the driven gear will move one thread pitch at the pitch diameter (ie pitch circle of the gear will move 3/4").
As the speed ratio of the gears is 40:1, this represents 1/40 of a full rotation of the gear so pitch circle circumference is 40 *3/4" = 30"
To get the pitch diameter from pitch circumference, divide by pi.
30/3.1416 = 9.55"