Energy / home energy renovation question

Only reason I'm posting this here is (a) I suspect other people have had to deal with the challenges of air conditioners on separate controlling technology and hopefully have a solution and there does seem to be a group of energy folk hidden in the crowd.

I've talked to design engineers but I have a challenge that seems to be quite difficult in the home energy market and I'm curious if anyone has any insight how to resolve it.

I have an old home with a boiler and water pipes for heating. In the renovations I'm hoping to get solar [problem solved] + a air to water heat pump to minimize my dependency on fluctuating natural gas prices (and Co2 impacts).

(1) I have an air-to-air mitsubishi heat pump for summer (controlled by remote control - which I want to hook up to the main thermostat to effectively manage it - though I haven't found a good home controller - any suggestions). There controller software is brutal - curious if anyone knows better.

(2) See if it is possible to replace the boiler with a heat pump but I need to have a smaller natural gas booster (combi unit) to get to the right temperature to be viable for the old pipes in the house (different size).

(3) Does anyone have experience with air to water heat pumps?

(4) To broaden it a bit - is there any home heating tech / control tech that anyone really is impressed by? From my perspective it seems to be a fragmented market with poor options if you expect certain level of quality software / performance.