Grumpy is correct. The firehouse is Engine 18, Battalion 4, District 1(2-2-1), Ambulance 84(BLS), and High-Rise Unit 6-4-16 at 1360 S. Blue Island Ave. District 1 was originally with Engine 42, Truck 3, Squad 1, Ambulance 42, Ambulance 93(BLS), and Command Van 2-7-1 on W. Illinois St. on the Near North Side, but once Engine 18's new quarters were built, I believe the District Chief moved there.
As for the Otis thing, I don't think it's a CFD-term. Like memory master, maybe the guy was good at handling elevator entrapments. Other than that, I haven't got a clue. The masks used in the show had their mouth-pieces removed from the inside of the facepiece so viewers could see the actors faces. Normally, their mouths wouldn't be visible.
The CFD currently operates one Aerial Tower, Aerial Tower 1, quartered with Engine 1 and Ambulance 41 on S. Wells St. in Downtown. It is currently a Pierce Dash 105' Aerial Ladder. It operates just like a normal Truck Co. does, just has a different designation. I'm not sure whether it's pre-piped or not, however, it is currently the longest Truck as far as aerial reach goes in the CFD. Other Truck Co.'s are 100' or 103'. At one time, there were 2 Aerial Towers in the CFD, and like Grumpy said, both were E-One 135's aerials, the tallest ladders the CFD has ever operated to my knowledge. Prior to that, also according to Grumpy, Aerial Tower 1 operated a 1974 Henrickson Morita 135' Aerial w/an Elevator to the top of the stick.
Coming from a personal opinion, the show Chicago Fire seems pretty over-dramatic and un-realistic to the way that the real Chicago FD does things.