1) Not sure of hazard level...did not see warnings from munufacturer
2) It has proven to be pretty durable in the limited testing I have had (Lakes frozen up here now) then again I don't fish for toothy critters. Does well against the rocks though
3) I usually use 2 coats and have had zero issues
4) I brush...cheap art brushes from hobby lobby 100 for like 5 bucks
5) Will not set up from ambient light...Need UV...i have done several bass baits and put them all ander the light at the same time...have not had any set up while waiting so you should be fine with that.
Hope that helps.