I think you've got 13.5 cu. ft. (3'x3'x1.5')

Anyway, an 80 cfm should move enough air...I think the best estimate is that you should be able to recirculate your air 3 times a minute. 80 cfm will be 6 times a minute.

As for the heat...you'll just have to check and see. One thing I've noticed is that the bases/ballasts of the big CFLs generate quite a bit of heat, so I know what you're talking about with the heat concerns from a 125w CFL.