exhaust fan sizing

I'd like to turn my single-car garage into a cigar lounge. I need advice on an exhaust fan. This is in a townhouse end-unit with a tiny single-car garage. It is about 10'x20'. The garage is next to a storage area where there is an existing 4" exhaust vent. I'd like to install an in-line fan from...

I had my basement finished but now realize that I am getting a lot of condensation and dripping on walls after showering. The bathroom is about 130 sq. ft. and has a shower, toilet and sink in it. Contractor put in a 100 cfm Utilitech fan and only a 4 inch duct. Unfortunately, he has walked...