I'm gutting my condo bathroom and before I drywall I want to solve my exhaust issue. Currently I have an exhaust input that I'm told vents to the roof, but no fan (I believe there is one on the roof?). Give the lack of window and air flow in there generally, I'd very much like to add one. Currently the exposed part of the duct runs parallel to to floor (i.e. left/right not up/down) and then turns 90 degrees so the opening is down and so that a grill reaches it easily (i.e. it comes down to the drywall on the ceiling). The duct and the opening are 6" square.
1) Can I cut off the end of it with the 90-degree bend and put in a fan in that spot with a side output to the duct and the "down" side being then aligned for the drywall ceiling finish?
2) Fortunately its close to where all the switches are going to go, but do these things use a lot of juice? Obviously will get its own switch but I'm good on an existing circuit that just has a few lights right?
3) The duct is also covered with some sort of spray-on insulation, sort of similar in texture to a popcorn ceiling. Might this be asbestos? Building is circa 1970 and hard to know what work was done at what later period.
4) What else am I not thinking of?