pmlapl:
Two of my servos rotate @ 0.19s/60 deg. The other: 0.12s/60 deg. I would need to know what the rotation rate is for each servo to keep the foot moving in a straight line.
Absolutely not.
To solve this problem properly you need to keep the speed of each servo below its maximum and directly control where each server is at any given time. To do that means calculating where you want each foot to be at each moment, and then do the reverse kinematic calculations to determine the servo positions to put it there, and then direct each servo to move to that position. A fraction of a second later you will do it again.
It's possible that your inverse kinematic calculation will take too long to do it for every single servo increment - in that case you would use the IK calculation to determine the current position and speed for each server, and use the speed to extrapolate future positions until you can complete the next IK calculation.