My return of serve is my biggest weapon, and although I am not a touring pro, 'getting ready from the feet up' sounds like the wrong way to think about it. Given the limited time everything needs to move as soon as possible towards the contact.
True, you need some kind of leg movement when the server makes contact, so that you can move in any direction quickly. However, as soon as you know the direction the ball is travelling you need to rotate your shoulders/hips and step into the shot. If you 'get ready from the feet up' the entire upper body will be late on a fast serve and you will miss the contact point.
Though, the leg movement is just as important as the upper body movement. You often see players standing still on the return, wondering why they cannot track position themselves for a kick serve.
There are two common ways to do the split step:
-An Agassi/Djokovic style hop http://www.youtube.com/watch?v=B8Qh-r77Sk4
(split step from the ready position a few inches forward)
-You can step into the ready position Murray Style: http://www.youtube.com/watch?v=i-wPMLwDc8I
Personally I stand as close to the opponent as I can, which depends on how good their serve is. For the average serve I stand about half a foot back from the baseline, for big servers I stand up to 3ft back, and for rubbish servers I sometimes wait more than a foot inside the baseline for their second serve to intimidate them.
Note: Standing more than a foot inside the baseline is more of a psychological game than a valid return technique, however it can work very well against certain players.