What else do I need to complete the system?

You need a compatible indoor air handler or wall head, a line set, refrigerant lines, and typically a wall bracket or pad. The condenser alone will not cool or heat anything.

Is 17,000 BTU enough for my room?

It suits roughly a large room or open area, but sizing depends on square footage, ceiling height, insulation, windows and climate. Have a load calculation done rather than guessing.

Does it work in cold weather?

Its 8.5 HSPF2 rating suggests solid heating efficiency in moderate cold. For sustained temperatures well below freezing, check the manufacturer's rated operating range before relying on it as a sole heat source.

What electrical setup does it need?

It runs on 208/230V, so it needs a dedicated circuit sized to the unit's rated current. Most homeowners will need a licensed electrician to run it.

Is R454B refrigerant a problem for service?

R454B is the newer lower-GWP refrigerant replacing R410A, and it is mildly flammable, so it needs A2L-rated tools and trained technicians. Confirm local technicians can service it before buying.