BaomainSzw26-40/D303.3D Universal Rotary Switch with Master Switch Outer Box 660V 40A 3 Position 12 Terminals 3 Phase

Q: What are the locations ot the output of the input locations 1 and 2?

The outputs and inputs are located on the mechanical dial. Use a multimeter to check current path

Q: I know this is designed and speced for AC, but is there any reason it could not do DC? Specifically 90V@10A Max (for a DC motor).

A switch is a switch, it doesn't matter if it is ac or dc. Amperage does count, however, and since this switch is rated for 40 amps your 10a motor should be perfectly ok.

Q: Will the terminals accept #12 wire?

In my experience, I had no need to use number 12 wire, but my assumption is the way the clamps work that it would hold # 12 wire. You could always put a feral on the end to make it larger if necessary.