I'm impressed you finished in the time you did with all of those navigation issues. I am a CSPS sort of person most of the time (cue sheet positioning system). Tom R. is pretty scrupulous about his cue sheets.
the Garmin problems sound like you have route recalculation on. I still haven't gotten everything I want out of the garmin, but we've settled into an uneasy truce. I like to hear the beep when I've just made the correct turn.