Nothing wrong with a heat pump if the rates are good, and the climate is
mild. in my area we see a few, in fact my dad has one in his home. Heat
pumps stop producing effective heat at 10-20 degrees. If you see allot of
time below that number gas may be a better choice, certainly at the prices
the OP stated.

As far as the metal venting for you heat and water heater you could easily
go with an electric water heater and a high efficiency furnace and do away
with the old metal chimney.
Again, you temperatures and energy prices will help make the decision.

Of course!

In any situation like this you "run the numbers."

Had the unit a GAS stove, if would not feel the same way. (I had put in a
GAS clothes dryer but that must be close to 20 years old by now.)

I have a gut feeling that 'lectric is the way to go with this unit. When
the time comes to take a decision I will ask the gas company to make some
recomendations. If they don't come up with a package and a price (like the
electric company often does), they will have one less meter to read.