My 2 cents:
1. Quickstep is international. No such thing as American
2. Lock steps are done fwd AND back. The easiest example= the V6 where after a spin turn there is a lock step back, a slow, the V, a slow, and then a lock step forward.
3. As a result, the lead is to move yourself diagonally, opening a little room for the follower to lock as she is forced by your movement to move diagonally.
4. Lock steps are not followed by a spin turn either necessairly or even usually. V6, 4 Quick Run, 6 Quick Run, Tipple chasse all have lock steps and are certainly not followed by a spin turn.
Please note that I'm no expert; this is just my understanding based on a couple of years of lessons.
Jerry Blumenthal