If you don't yet have a sawdust collection system set up in your workshop, an intermediate step is to use plastic trash bags under a tablesaw. Clip the bag below the tablesaw with snap clothespins. The sawdust that does not fall in can be scooped up and tossed into the bag. Also check out the options now available for using your wet/dry vac to collect sawdust from individual tools.
Bathroom fan fixtures can poke into the attic insulation and create a pathway for air leaks. Caulk around them from below with high-temperature flexible caulk.