Without knowing the exact product that you are applying it is difficult to say how nasty it is. It could be toxic when you spray it because of the solvents that carry the primer/paint, or it could be toxic from a chemical that's in the primer/paint-examples of this could be heavy metals or isocyanates.

As far as the dust goes...alot of primers/paints lose their toxicity after their solvents off-gas and the product cures. A big problem with sanding can be if there are heavy metals in whatever you are sanding. If you're worried about lead you can go to Home Depot and get a lead test kit of a few bucks. They are about the size of a cigerette and are easy to use. I think they might also detect some of the other heavy metals.

I'd be surprised if there were any heavy metals in the epoxies that you have but you never know. I'd suggest contacting the manufacture and asking to see the material data safety sheets (MSDSs)for the different products. Let me know if you need any help tracking that stuff down or interpreting what they mean.

Alot of the previous suggestions are really good. Avoid kicking up the dust. If you use a shop vac, try to use one with a HEPA filter - these are really good at collecting the dust without blowing it out the other end. Without the HEPA rating the vacuum might just put smaller pieces of dust back into the air.

Try to avoid sweeping and blowing things off with compressed air. Also, alot of painters i know actually change clothes in the garage because they dont want to carry things into the house. I'm thinking this might be overkill if you're just doing it as a hobby, if it's your daily job then we might want to talk a bit more.

Sorry if I'm rambling...prolly more info than you want