If you are just going to use an airbrush get a fan at least 200ish cfm, 350ish would be great.
Dont even think about using a rattle can in something this small.
I bought a 1HP shop exhaust fan and it handles a spray can just fine.
I dont mind helping more and dont take this as a brushoff 
but first search this forum for "spray booth" and read up on what has already been discussed. I think you will find enough reading material to take you into the wee hours of the morning and probably answer 90% of your questions.