Procedure for purchasing real estate - what must be checked beforehand?

1,000 EUR is a reasonable price for such reports. If it's a bit less, you're just happy.

I can't confirm that. I paid a little over €610 including VAT for the report at the end of Q1 2021 in the northwest of Bavaria. It's already 2.5 years ago, but prices shouldn't have risen that drastically.

Even if it costs €800 now, it would definitely be worth the price to me.

By the way: I'm a "regular customer" ;)

It is sometimes recommended to conduct a soil survey BEFORE purchasing the plot.
Here we ask ourselves whether this is even feasible in practice?

Usually not. Especially not when you have to act quickly to get a desired property at all.

Until now, we assumed that a soil survey would only be conducted once you already own the plot and are about to start building a possible basement?

No, even houses on slab foundations need one.

What you can do: look at the neighboring buildings, are there already others who have built new? Ask them how the soil behaves. Then you at least have a reference, even if not for your own plot.
Also look at the street in general, what condition and what kind of development it has. How does the rainwater infiltrate, is there a sidewalk, could costs arise for you, is there fiber optic etc.

Regarding the parking spaces: you can easily pave your yard with coarse gravel if gravel also counts as part of the bound surfaces. Otherwise, as already mentioned, use the old parking spaces or pave over the old pavement.

Otherwise, you are already thinking quite well and not too much :)

We are currently looking for a house/ and have set our sights on a specific property. This is a small house with a basement from the 1960s. However, since it is in poor condition and too small for a family, it would mean demolition in our case. [...] The only passage we do not quite understand is: "Newly created parking spaces and garage driveways must be paved with water-bound material."

Oh, is that still the same property as in January? Yvonne has already said that the soil conditions are relevant not only in case of basements. However, a basement over sixty years old is also a mini soil report: what leads you to the opinion that the property is in poor (and even demolition-worthy) condition? The zoning plan quote seems unusual to me for a zoning plan that would have already been valid at the time of the original construction, and the wording strangely vague.

Hello Häuslebauer3,
I would definitely obtain the following points before purchasing the plot:
1. Land register excerpt
It should never be older than 3 months (therefore, I would rather obtain it myself and not use the one from the current owner, which might already be very old). There should be no unusual encumbrances recorded here.
2. Development plan
You have already taken care of that. However, I would definitely also get in touch with the responsible building authority in advance to discuss your ideas and ask for an assessment. Making contact at this stage always helps!
3. Contaminated sites information
Instead of a soil report, you can definitely take a look at an excerpt from the contaminated sites register. Additionally, it can always be stipulated in the purchase contract that if unusually high costs for soil remediation occur (for example, over X EUR), you can either withdraw from the sale or the seller pays. This is always a matter of negotiation and actually not unusual at all in practice. Alternatively, a suspensive condition can also be included in the contract.
4. Register of building encumbrances
Also obtain an excerpt here to make sure that no one else has rights to the property that could restrict you in any way.

For some documents, as you correctly wrote, you need legitimate interest. Therefore, simply get a power of attorney from the owner; this is also common practice.

By the way. I am not allowed to post links, but all of this is really explained very clearly at Grundstücksdienste. There you will also find an overview of the sales-relevant documents and how a review process works, as well as, in my opinion, very valuable tips on the topic of buying and selling property.