Can it power a whole house?

Yes, at 15,500 watts on gasoline it can carry most whole-home loads, including central AC and a well pump, when wired through a transfer switch or interlock. Propane output is lower, so check the load against the propane rating.

Does it come with a transfer switch?

No. It has two 50-amp outlets for use with a transfer switch or interlock, but the switch itself is a separate purchase and must be installed by a qualified electrician.

It is a conventional open-frame generator, so expect noticeable noise at high load. It is not a quiet inverter unit and is better suited to a detached garage or the far side of a yard.

Gasoline or propane: which should I use?

Gasoline gives the full 15,500 watts. Propane avoids fuel going stale and is easier to store long-term, but it produces less power, so plan loads accordingly.

What maintenance does it need?

Change the oil after the break-even period and then on the schedule in the manual, keep the AGM battery charged, and run it under load monthly. The 5-year parts and technical service warranty covers defects, not wear items.