Does the Manual J show my house will be at 70℉ when it is 5℉ outside?
If you have no ductwork ask, “Can you quote this 1) with ductless units and 2) with ductwork in the basement for the ground floor plus ductwork in the attic for the upper floor?” Also ask for a quote for radiant-floor heating, this was surprisingly cheap in our rental house (but this will not do AC for you). Make sure the attic work is well insulated or you will get ice dams.
I have not tried AC using cold water in radiators. Some manufacturers say it can be done, but I doubt it without getting pools of condensation on the carpets.
For forced-hot water radiators, make sure the Manual J calculation is done with a water temperature of 110℉ not 140℉
How much money will I save on heating if I am paying 23c/kWh for electricity? How much if I am paying solar rates (5-8c/kWh)
How much for a heat-pump hot water tank? How much will it save me per year?
How long is the warranty, does it cover parts and labor?