Can the air-to-water heat pump also be used for cooling in summer?

Exactly. When I think about last summers... no matter how well you insulate. If you don't like the heat (anything above 24 degrees)... you need air conditioning :) I count myself among those. In my office, 6-8 screens also generate heat for about 10 hours a day. When it's 20 degrees outside, I have 25 degrees inside with the window open. I already need air conditioning in autumn and spring.

Especially when well insulated, the heat inside rises quickly in summer, being hotter inside than outside. After all, that is the main task of all the additional insulation: to keep the heat inside.

Hello, what do the preparatory measures include?

Climate pipes, condensate drainage, and electricity installation - I got installation boxes where everything is laid inside, and now they are plastered. I’ve even already wired and hung the remote control for downstairs :D

Yeah, that's how I would do it too, but it helps even more if you already have a specific model in mind so that you lay in the right cables, because there are differences.

There are different thicknesses, but with small systems with low power, you don't really have to worry about that.