We are looking into using a lead screw, but we are unsure of which motor to use as we need to calculate based on thread density, diameter of the lead screw and what motor, in order to figure how many rpms we would need and the torque. What is the best way to figure out the travel distance per second, torque and rpm required?

http://www.daycounter.com/Calculators/Lead-Screw-Force-Torque-Calculator.phtml

Both show the equations.