ᐅ Building permit application submitted / unresolved technical details / looking forward to suggestions

Hello everyone, our planner has now submitted the building permit application and asked us to consider a few things (on one hand, they want to start with the structural calculations, and on the other, to compile the documents for the tender).

17.5 cm (7 inches) sand-lime brick or aerated concrete: so far, we preferred sand-lime brick because of its thermal mass. We were told the cost is roughly similar. Aerated concrete offers about 25% better U-value (in our wall construction). Sand-lime brick, however, provides better thermal mass and sound insulation (though the latter is less important). Interior walls will be built with sand-lime brick. Can anyone strongly recommend one over the other? (cavity wall with insulation and facing brick)

Recessed spotlights or regular lamps: this might also be relevant for the structural load. I did a rough calculation – if we have to count €60 (euros) per spot, that could add up considerably. Some say spots are not ideal from a lighting perspective either. I’m leaning against them, my wife is in favor. Is this just a trend, or is it truly better than regular fixtures?

Tiles or other floor coverings: we have mostly tiled the ground floor. Now the question is what to choose for the upper floor – I would also lean towards tiles here. We had briefly considered cork – does anyone have experience with that?

Ventilation: it’s almost certain we will have a decentralized ventilation system with heat recovery—most likely cross-flow (no inverter - I know the pros and cons, but we would probably never feel comfortable with a central system). Does anyone have specific models to recommend or advise against based on whether they can sleep well with them or not? We have already visited five houses with central ventilation systems to “listen” and talk to the owners. Three of them have the system on the lowest setting or turned off because it bothers them (which kind of defeats the purpose). Am I allowed to mention companies here? I have read something about Blue Martin – they are expensive and supposedly very good – but it’s always hard for a layperson to tell if it’s just marketing.

Ground-source heat pump: is deep drilling better or are horizontal/spiral collectors preferable? Is it possible to cool with horizontal/spiral systems in summer as well?

Additional cost for engobed roof tiles: we need to decide on roof tiles, but the building supplier wouldn’t give us price details (they said prices would be sent directly to the builder). Can anyone roughly estimate the extra cost for engobed matte clay tiles compared to non-engobed matte clay tiles? Is it worth it or more about appearances during the first year?

Thanks for your opinions and best regards.