Hi Ben,
ad #2: changing from one camera to another in the programm-monitor means making a cut in the TL; for practising make your switches und delete all the cuts afterwards.
ad #3:if you want to make differnt versions just put a copy of your multicam-clip on V2 (or at the end of the TL) and start over; or select the area you want to re-cut, delete edits and draw back the remaining MC-clip.
Jo