Typically, squirrel-cage fans work really well, since the fan does not exhaust through the motor. Stay away from range hoods and bathroom exhaust fans. Get a fan big enough to pull the vapors into the booth and then push them out your exhaust ducting. Capture velocity at the booth face should be about 80-100 feet per minute (fpm). Example: If your face area is 4 square feet (2'L X 2' W), then the MINIMUM airflow you need for a fan will be 80 fpm X 4 sq.ft. = 320 cfm. Depending on the length of your exhaust ducting, you should probably bump that 320 up by about 20% or so. That will also account for filter resistance (which is slight, but it's there). By the way, stay away from plastic or vinyl clothes drier hose. Get at least 4" aluminum flex duct, and avoid long vertical runs and right angle turns, as that increases friction loss on the system and decreases duct transport velocities. The shorter your ducting runs, the better.
The idea behind filters is that they are there to keep paint pigment residue from depositing on the fan and along the exhaust ducting, and decreasing your overall airflow (as well as increasing fire risk). Once again, I would avoid most furnace filters, since they will catch a lot of the big stuff, but allow most of the finer pigments to migrate where you don't want them. You might consider checking with your local auto body paint shops, or paint suppliers, and seeing what kind of filters they use or have available.
Just my opinion. Hope this helps a little.
Gip Winecoff