I am sorry but these questions are routed to the supplier. So although I can answer questions about the product I can not speak effectively about Home Depots installation services. I do know they vary by location. I would suggest you contact your local store. I can offer you this. This furnace is specifically designed and built for use in a mobile home. Mobile homes are typically manufactured and sold new with a furnace installed at the factory. Thus I would say its safe to assume that when someone purchases a Miller furnace from The Home Depot they are replacing the Miller furnace that is in there mobile home; like for like. Thus the installation should not be that involved. I certainly could be wrong, which is why as a trades person I never quoted prices without seeing the job as every home is unique.
When AC is installed with a typical furnace, an A coil is installed in the plenum to pull the heat out of the air as it passes through. Obviously the flame does not run but he blower runs to move the air. The furnace is thus acting as what we call an air handler. This furnace is capable of that as most are. What I can not tell you is if that would be a practical installation in your situation as I am not on site.
The version with the "T" in the model number is the new version. The non T version is out of production. The T signifies that the new unit is built with a 5 tap ECM electric motor as apposed to a shaded pole motor. . ECM stands for Electronically Commutated Motor, These motors are much more efficient and furnace this usually translates into real savings on your electric bell. I actually change the motor in my furnace to an ECM. It made a noticeable drop in my electric bill and makes less noise. Shaded pole motors spin because of the 60 cycle pulse built into the electric current itself. With ECM motors this power converted into DC. The electronics get the motor spinning and then DC current is applied. This ussually drops electric bills noticeably.