I always add more hardener to the resin to make sure I add enough. Sometimes it sets up to fast on me. To get that stuff off your fingers: well, I use lacquer thinner or M.E.K.
On some brands of fiberglassing resin it takes longer to cure. I find out whats the quickest and use that. I got some resin and hardener from home depot and the auto parts store. Sometimes you gotta watch the stuff they sell, sometimes aint no telling how long its been on the shelf. That stuff does has a shelf life before it starts breaking down. The stuff I use (they are all basically the same) its 14 drops of hardner per ounce of resin. I usually do about 20 drops of hardner per ounce of resin.