So who should I side with from my perspective? Also I will have a wall mounted air conditioner in the room for cooling as well.
I see that you want to finish-off an unfinished attic. I'm not sure why you want to install an attic fan. Attic fans are usually installed into UNFINISHED attics. With that, ...
Consider these things: You don't insulate the attic roof-rafter-space w/o, first, installing Soffit Chutes. You'll want to install a Ridge Vent too for the chutes to vent the hot air. You want to make sure that your attic FLOOR can carry the load of another room. (Do realize that when a home is built w/an unfinished attic, it may NOT be built in such a way to support the load of a room, etc. ...) If you're planning on heating and cooling the attic w/your current HVAC system, make sure it's rated to carry that 'load'. (Your current system may be UNDERSIZED when you include the finished attic ...) How would one escape the attic if there's a fire? (Do you have a 2nd exit, or an "emergency exit"?)
I guess I could go on and on. Find yourself a good book on how to finish and unfinished attic. (They have them for attics and basements ...) That would be $$$ well spent.
My best to ya and hope this helps.
Jay J -Moderator
PS: God Bless America!