Air Lift Wireless 25980 and 25980EZ Installation video 

The compressor can be mounted in any orientation but the manifold is not able to be mounted upside down or with the electrical connector facing down. It could be mounted on its back, face up under a seat.

You could wire the power to one of the switches but it would offer no control over these kits. Cutting power would serve no purpose as the 2nd gen compressors will sleep on their own after the vehicle has been parked for a short time and only need power and ground. Key on or switched power is no longer necessary.

The manifold is not meant to be used with a constant air source like a tank. They are designed to be used on demand and the compressor will only run when air is needed in the air springs.

The pink wire can be connected to a keyed power source to turn the system on and off but it is optional. Without the pink wire the wireless one system will enter a sleep state when the vehicle is not moving and it can only be woken using the remote, the phone app, or vehicle motion. This new system can be installed by connecting just the battery positive and ground.

The compressor is grounded to the frame. The battery ground is for the manifold which functions as the valves and the brain for the system.

A different compressor could be used but it should not exceed the 15A that the fuse and the wiring is rated for.