Is financing feasible? Single-family house 155 sqm

What do you mean by directly?

Well, the (admittedly attractive) minimum waiting time doesn't help you if you need 13 points to get promoted, but you "only" have 11 points and still have to wait longer than a year.

Do you also get an allowance for your family, that is per child and spouse? No? What a pity.

How high are these allowances?

In Hessen:

Marriage: 138 gross
For child 1 and 2: 119€ gross each
For child 3: 370€ gross
If both are civil servants, the allowance is shared.

How high are these surcharges?

Currently no time to look up the exact figures, but similar to Hesse, with two children and a marriage it is just under 400 euros gross.

Well, the (admittedly attractive) minimum waiting period doesn't help you if you need 13 points to get promoted, but you "only" have 11 points and still have to wait longer than a year.

There is nothing about this in the State Civil Service Act. Where does it say that in Bavaria? I think it is at the discretion of the employer.

There is nothing about this in the State Civil Service Act. Where is that stated in Bavaria?
It is at the discretion of the service authority, I think.

Yes, this depends on the overall budget allocation. Promotion is based on performance, suitability, and qualification.
This is recorded through an evaluation.
Based on the budgetary resources, possibilities are determined. For example, 10 promotions from A9 to A10.
If there are only 10 civil servants with A9 within the authority, all are promoted. If there are 11 civil servants with A9, a ranking list is created based on the evaluation. Subsequently, further points such as time in the same rank, etc., are considered.

As far as the federal government as the service authority is concerned. Waiting time, by the way, is 1 year.