Help! for a New Owner of an Old Boat

[GoFish]

First time on this forum (mostly a surf guy) and I could sure use some help. Purchased an '81 Steiger 21' last fall and am trying to get it painted and ready for the season. It appears to have MANY coats of paint, and I'm trying to sand it before painting using an orbital sander and an 80-grit paper. IT'S KILLING ME! Looking to be a twenty-hour job. Any pointers to speed the chore?

Also, should I be filling the dents and dings in the fiberglass before I paint? With what?

Any suggestions appreciated, as I clearly don't have a clue what I'm doing. Thanks!