I'll try to answer your questions.
A heat pump (HP) is like an air conditioner (AC). It is a separate unit vs. the furnace or air handler (which moves the air and will be the back-up heat).
Most HPs, to be most efficient, need to shut down around 30 degrees. Then the back-up heat (gas, propane or electric) turns on. The "variable speed" (not 2-stage) Carrier Greenspeed is the most efficient HP and doesn't need to shut down early.
Some utility companies will give a big (rate) break to a home that is all electric. You then would need electric air handlers (with staged electric heating). I believe you can still have the LP hot water heater, stove and dryer to receive the special rate. Something to look into and consider since you will be heating mostly with wood.
I would recommend two systems (that'll be 4 major pieces, 2 inside and 2 outside). Both furnaces could be located in the basement or a utility room for the second floor system is even better. Both furnaces should be designed to have zoning. Note: Carrier also makes a killer (Infinity) zone system.
Regarding the furnace efficiency needed. I like the 90+% AFUE because they use (you need to ask) outdoor combustion air. This should be an obvious reason in itself. But it also keeps the units quieter than the 80% furnaces. Of course, if you go with electric AHs none of the venting or combustion air becomes an issue.
The major problem you'll face is finding a good HVAC contractor to properly size and install the equipment. Make sure to go with "variable-speed" blowers and good air cleaners. Carrier offers the best options there as well. Some on this site say they don't like Carrier. However, ALL the technology we now enjoy, came from Carrier's R&D.