There are all kinds of vacuum dust collection setups possible, of course, but here's a dust "solution" nobody talks about:
If you can slow the sander to 10-20% of "normal" speed, dust production is very different. Instead of shooting dust all around, it can cause dust to fall more or less straight down. By using pulleys, I slowed our 6x48 belt to a bit less than 500 ft/min, and with a DC motor and variable speed, I have the 1x42 running at a slow crawl if I want. Dust gets vacuumed off the floor instead of walls and ceiling. . .
If you can repurpose a central vac system they're designed have pipe run to them and they vent outside. You can often pick them up for next to nothing. You might find one at a restore.
You may want to review your plans to generate wood dust with the insurance provider for the business. OSHA and the NFPA have pretty strict rules about occupational wood dust exposure and fire prevention. If you can get by w/portable sanders (I use a portable ROS sander inverted in a vise) I suggest checking out Festool's sander line along with a good HEPA filtered vac. The good vacs are very quiet. Festool and Fein are the best. Another option is to attach a Mirka Abranet backing pad and pad protector to your existing portable sanders and use Abranet abrasives along with a HEPA vac. http://www.mirka-usa.com/pdf_files/LI-MA002_abranet_marine(rev).pdf The abrasive lasts a long time, zero buildup of melted finish, no stearates and capture the dust within ~1/2 mm from its creation. You protect yourself /co-workers/customers and don't open a can of legal worms.
For bigger stationary equipment I suggest you Google Bill Pentz for an exhaustive review on wood dust collection. You'll probably figure out that to do it correctly is very expensive and a lot of work.
I have a small shop in my house. Tried sanding inside just does not work. I put wheels on my thickness planer so I can push it outside when in use. I have an orbital sander,again I carry it outside. I still wear a sanding mask as breathing wood particles is not a good way to go. Sorry no ideas for you other then take it outside
i don't think osha would be too pleased with your proposed lunck room / repair room co-habiting.. too many substance/ health conflicts.
I was looking for a good 18v dust buster-type product for bench cleanup and found one made by Porter-Cable that uses the same batteries as their cordless tools. The P-C cordless vacuum has a port for attaching it to P-C sanding and cutting tools for dust abatement.
ZipWall makes clever tools for construction dust control. You might use some Zip Poles, a Zip Door and plastic to section off a small area for sanding.