My sub box is carbon fiber instead of fiberglass. As said above, I would not want to directly inhale the dust, mild exposure is probably ok, but I wouldn't want to breath dust from anything I am sanding.
Second,
Don't expect to get all the lines nice and straight, unless you go through with a toothpick and straighten them. The best way i have ever seen to apply resin, if you have excess resin, is to lay out some plastic on the ground. Lay out the cloth weave, either carbon or fiberglass. Then, pour resin onto the fiber and roll it out with a roller [a metal roller wont absorb resin and wont leave lint]. Flip and repeat, voila, you have a saturated piece of cloth and it helps keep the lines straight. [This is an industrial method for wetting out fiberglass and carbon fiber pipeline repair kits].
I can answer lots of questions probably, carbon fiber vs. fiberglass was one of my extended essays my senior year.