You are welcome.
1) correct, the joystick / victor controls motor speed and the pot is like a position switch, in that it limits the range the motor is able to work in. If you want the motor to work with a window of x degrees rotation, that can be controlled by setting the limits. The other method is to build in hard stops to mechanically stop the rotation- thus stalling the motors and potentially destroying parts - pot limits work great, once you get them tuned in.
2) here is a hyperlink to small parts inc. - the tran torques can be purchased there -
http://www.smallparts.com/products/d...s/ttq-mttq.cfm
or from fenner -
http://www.fennerprecision.com/trantorque.php
Best of luck,
Mike