Given your resources the key for your safety is a NIOSH-95 rated dust
mask that fits well and is worn whenever you're in the shop. What is
the particulate efficiency of the vac filter? You'll want a HEPA rated
filter for maximum safety.
If you use the filter-and-fan, use a good quality filter like the 3M
Filtrete 'Ultra Allergen' filter. This captures about 60% of the 0.2
to 2.0 micron particle size on the first pass, so it actually helps to
improve the air -- marginally. And if you put that fan in the window
to exhaust outdoors, make sure you make up the air from another open
window so you don't end up with your combustion appliances
'backdrafting' into your house.
It is possible to make a shop-built air cleaner with 1/2 sheet of
plywood, a couple furnace filters, and a discarded HVAC blower fan and
motor. The fan/motor can usually be had for a case of beer from the
local HVAC company. Again, the key to this unit's effectiveness is all
in the filters you supply it with.
You will find an excellent online resource on dust collection at this