Check with your insurance agent to make sure having a bike inside won't allow the insurance co to avoid paying a claim in case of a fire.
Don't forget to Install CO and smoke detectors.
Install a vapor barrier and drywall on the ceiling to make it harder for fumes or fire to come through your floor.
As previously suggested, install an explosion-proof fan, and buy one of these for shop rags:
Re: fans, perhaps one made for a boat engine compartment would be cheaper than a paint spray one.
Careful that you don't undermine your foundation. Google "underpinning".