On the autopilot/GPS question...
An older autopilot can be set to "track" mode. It follows the given heading, then uses the deviation indicator to modify the heading flown to keep itself on track. I've never found this to work especially well. With my old autopilot I just put it in heading mode and manually twiddled the heading so the track indication on the GPS was correct (i.e. taking account of crosswinds).
Newer autopilots and GPS have something called "GPSS" which essentially does automatically what I just described. You select GPSS mode and then the GPS sends fake heading information to the a/p to keep the aircraft flying in the right direction. It also has the nice feature that if your course involves turns, the a/p will follow them (including leading the turn) without you needing to do anything.
The latest GPS (Garmin 430W/530W) have even fancier GPSS features, so for example you can fly a hold or a DME arc without touching anything.
n5296s