What is the procedure after finding a plot of land?

Hello! By now, I have so many question marks over my head that I hope you can shed some light on the situation.
My husband and I have the opportunity to purchase a plot of land in about 2 months, which is currently being developed alongside 3 others. We want to build within the next six months.
How does the financing work if I want to get a loan right away that includes the house construction? Does this mean that I already need a concrete offer from a construction company to present with the financing request for the land? Because the exact details of how large the house on the plot may be are not yet determined. Or can one first withdraw the amount for the land and then have a certain period to cover the total volume of the construction project, so that the interest still applies and it is considered one and the same loan? As you can tell, I probably still need some basic knowledge on this topic ;-)

Equity? What is the land supposed to cost? In Brandenburg, the square meter should be affordable.

Equity amounts to €30,000, which is half the price of the land. However, if house construction proceeds relatively quickly afterwards, isn't real estate transfer tax usually demanded on the entire project? The land is, however, free of developers and with 2 different purchase contracts for the land and the house, the tax should actually only be calculated on the land? With the rather small equity, we wanted to use as little of it as possible to be able to pay the incidental construction costs.

Equity amounts to €30,000, which is half the price of the plot.

See if you can perhaps finance the plot temporarily through the family.

If house construction follows relatively quickly afterwards, isn’t there usually land transfer tax charged on the entire project?

A quick start to construction is certainly what most wish for, but it is often not reality. Plan for at least 6 months. It takes at least 2 months before the plot belongs to you. A building permit also often takes 3 months or more.

The plot, however, is free of developers and with 2 separate purchase contracts for the plot and the house, the tax should actually only be calculated on the plot, right?

If there is no economic connection between the plot owner and the construction company, you have a good chance of paying tax only on the plot.

With the limited equity, we wanted to use as little as possible of it in order to be able to pay the ancillary construction costs.

Where the equity flows is initially irrelevant. You should try to pay many small expenses from your ongoing net income anyway.