I came upon a similar problem with trailer wiring while on a trip with my tent trailer. We stopped for the night at a camp ground.In Virginia, i think. Raining cats and dogs! Sat in caar until it stopped, then set up the rig. Later on, a fellow camper came over and asked me if i could fix his trailer to car wire plug. seems he forgot to remove it from the receptacle, got the hitch off the ball, and pulled the car away, along with the plug! So, i sat down and fixed it for him. He told me the lights would blink when going along, so i fixed that problem, too. Made up a separate ground wire with a male/female detachable plug. Took 2 hours of work. Made him extremely happy when i refused payment for the work! Somebody once said:"When Rusty Jones goes camping--he takes his garage along, too!" I did! Had a floor jack, safety stands, tools of all kinds, everything i might need. I couldn't afford to go to a dealer or repair shop!

For everything I have read, yes it makes sense that the orange wire replaces the white wire for a heat pump configuration. The white wire is used to turn on the furnace for heat, and the yellow wire enables the condenser for cooling. But you have a heat pump, therefore when you are in heating mode, the thermostat will turn on the condenser (yellow), but it must also enable the reversing valve in the proper direction. The orange wire is used to control the reversing valve. Call the Hunter technical support line at 1-888-830-1326 from 8am to 5pm Central time. They should be able to review this with you and guide on which thermostat is appropriate for your set up.

Sounds like you've hit most of the issues. Don't forget the in-use covers on the new outdoor receptacles. All you need for lighting is a switch somewhere in the room to turn it on. Putting a an additional (three-way) at the second entrance is not a bad idea but not required by the code.

AC circuits don't have positive and negative. You have grounded (neutral) and ungrounded wires. It's impossible to tell for sure, but what I think likely happened is you had was that you didn't have four wires connected together. I suspect one wire is the feed from the fusebox/breaker panel, it was tied to a wire running ot the light switch. Another wire was the return from that switch that connected to the one side of the lights (these are all the ungrounded wires), then you have the other side of the lights connected to the grounded (neutral) wire from the fusebox. A fourth wire goes to the receptacles. Here's what I'd suggest you do. (Obviously turning off the power at the fuse/breaker while manipulating things). Disconnect the four wires you've got bundled. With a meter or other tester find which one has power when they're disconnected (this is the one from the panel). If you have an ohmmeter you should be able to identify which of the other three go to the switch. They will have near zero resistance when the switch is on and practically infinite when it is off. Connect the remaining wire, the one you identified as the feed, and one of the switched wires together. Connect the other one to the new fixture (and use the old single wire to connect to the other side of the fixture).