Not all brands use the same control system for heat pumps. Many have
special wiring requirements. The common is often blue, but some use
brown or black. The electrons don't really care what color insulation
is on the wire, it just makes it easier to service.
R=red$ Volts Hot
O=Orange=Reversing Valve Energised in Cool Mode
B=Blue$ Volts Common
There may be other wires for service lites, but that is normal wiring
R,W,G,B connect at the indoor unit, All 6 connect to the thermostat,
All but G connect to the outdoor unit. If yoy don't keep the color
code consistant, you could fry something. If there is a splice in the
cable where there is a color change, you will most likely need a meter
anf know how to use it.
Other brands like Rheem/Ruud, Amana, Weather King use completely
Setback thermostats work best when equipment is too big. If your heat
pump is properly sized, you will not have enough capacity to do
recovery, especially in heat mode.
How you heated your home without strips in extremely cold weather I
don't know. You must live in a mild climate.