Hey, I'd advice reading all of the safety threads on the board and all the labels on the back of the products. You definitely need a respirator for resin and if you follow the MSDS you need one for bondo. I'd personally use a respirator for just about everything you use such as resin, fiberglass, bodyfiller, etc. Make sure to purchase a 3M respirator with organic vapor cartridges, and wear latex/vinyl gloves. If you need non-toxic resin I'd go for Smooth-on. Hope it helps.
-Jason