With regard to the epoxy / polyester question - use epoxy. Epoxy adheres well to cured polyester (even better than polyester does). HOWEVER, polyester will not adhere well to epoxy - and gel coat is polyester. If you intend to gel coat, repair the boat with polyester resin.

That said, you should find a good glass guy - that's going to be a pretty tricky repair. I'm no expert but I've done a good bit with fiberglass in the past (vacuum bagging, mold making, etc.) but I would probably take it to someone. Sorry to see that.