Overnight guests per year: only if someone is not fit to drive.
Once a year or 20 times a year?
Number of parking spaces: 1 parking space in front of the garage.
This is usually not allowed. The question is how many parking spaces you need to provide. Is there a site plan? The uploaded plan is just a cluttered picture – where is your property?
conservative or modern construction: Modern
I don’t see that. The south side looks sh.., not nice!
I have found information online with up to €2200 per sqm, isn’t that unrealistic?
For Bavaria, I would use €2500.
This is 5.94 sqm per floor.
You can deduct as much as you want: when calculating per sqm, the entire area counts, not according to living space calculation. I’ll put it this way: office on the left, WC on the right, living room on the left, kitchen on the right, and somewhere in the middle dining and stairs is not the art. Planning is somewhat more intricate – if I come across such a strange bedroom layout (I can’t even think of a question like what you had in mind), then I start over. For more details, measurements, furnishing, and a site plan of the property are missing.