Hi folks, need some input on this...

The images attached show the old, moldy humidifier that is part of our home's central air system. We haven't used it in 2+ years of home ownership because: 1.) we haven't felt the need and 2.) we know it's in awful, molded shape.

I don't have a great understanding of HVAC but am comfortable learning and getting handy. So, I have a few questions to understand how complicated the removal of this unit would be...

1. After removing the unit, is there still a need for the PVC "drain" hose that runs to the little pump on the floor? If not, could I leave the PVC pipe, but just remove the
2. I should be able to easily remove the thermostat and wiring for it (which comes from the receptacle on the other side) as there'd be no need for that any longer, correct?
3. After removing the unit, how would I properly fill that gap? Just cut a specific type of sheet metal fastened in place?

Thanks in advance!