Have a friend who installed radiant floor heat cost megabucks to
retrofit.

his observation the air in the rooms stagnate, he is now looking at
reinstalling some air ducts for air circulation.........

smells and such linger forever....

Gas heat will be the cheapest to operate. electric always costs far
more per BTU of heat.

I suggest if your remodeling you INSUATE WELL!! all walls cielings etc.
sales feature at resale time, and saves big bucks while you live there.

with such a large home you might consider making it 2 units or 2 unit
capable during remodel/

subdivinding with the right tenant can help pay the long term bills and
permit a nicer reovation too.

example do attic apartment first, live in attic apartment while
remainder of work is being done