Selecting property overwhelms us

Are the 245€/sqm with development included? Because for us there were another 100€/sqm on top of that.

You first need an overall plan.
600,000€ - 200,000€ for the land leaves 400,000€.

Of that, 100,000€ for additional construction costs, garage, outdoor facilities, kitchen, furniture...
Leaves 300,000€ for the house. That probably results in just about 120sqm without a basement.
Do you still want such an expensive plot?

With a total budget of 600k, I would choose one of the smallest.

Sorry, we are really complete newcomers in this field...

You should simply look at houses on the internet that are allowed by the development plan.
Then, in parallel, google the topic of construction costs – there are many posts that tell you how to calculate well and, even more importantly, how to evaluate the catalog prices of construction companies.
Almost everything is allowed on your site (development plan point 4 is very complicated and you have to have it explained) ?

That's how we would want it too, unfortunately we somehow lack the imagination to picture a house on one of the plots...

Drive to older residential areas and take your walk there and compare them with new development areas. But don’t be fooled by the age, instead look at how carports and houses are positioned.
Try to get the measurements by using the rule of three from the drawing. The 484 sqm with 25 meters depth results in just over 19 meters in width. That is enough for a double garage/carport, a 10-meter house, and a 3-meter border distance.
Draw the plot for yourself, any one or even several, place templates of 8 x 10 for the house (or 9 x 9) and a double carport of 6 x 6 and play around with it once you have looked at house floor plans on the internet.
Window areas facing south or west, also the house garden there (the front yard is the one in front of the house).

Overall, the costs should not exceed 600,000 euros. And as you can see, unfortunately we really have no clue about anything yet. I don’t think we’ll be able to afford a basement...

484 sqm x 245 with purchase incidental costs 120,000€
140 sqm house 350,000€
50,000 construction incidental costs
Carport and outdoor facilities 50,000€
30,000€ buffer.
And suddenly, it’s 600,000€.

Take one of the 484 sqm: they have a nice southern location, are not close to the streets, and don’t have “expensive” corners.

Don’t preserve your ignorance, but modesty. Some newcomers want this and that, and without this and that it’s not a house. Everything must absolutely be there, but financially not feasible at all.
140 sqm for 4 people is enough for 4 people if you do without a fireplace, dressing room, and mega pantry.

You should simply look at houses on the internet that are permitted by the development plan.
Then Google the topic of construction costs in parallel – there are many posts that tell you how to calculate well and, even more importantly, how to evaluate the catalog price from construction companies.
Almost everything is allowed for you (development plan point 4 is very complicated and you have to get it explained) ?

Drive to older residential areas and take your walk there and compare them with new development areas. But don’t be fooled by the age; instead, look at how the carport and house are positioned.
Try to get the dimensions from the drawing using the rule of three. The 484 sqm with 25 meters depth results in just over 19 meters in width. That’s enough for a double garage/carport, 10 meters house, and 3 meters boundary distance.
Draw the plot, any one or even several, place templates of 8 x 10 for the house (or 9 x 9) and a double carport in 6 x 6 and play with it when you have looked at floor plans for houses on the internet.
Window areas facing south or west, also the house garden there (the front garden is of course the one in front of the house)

484 sqm x 245 with additional purchase costs 120,000€
140 sqm house 350,000€
50,000€ incidental construction costs
Carport and outdoor facilities 50,000€
30,000€ buffer.
And suddenly, it’s 600,000€

Take one of the 484 sqm: they have a nice south-facing position, are not close to the streets, and have no "expensive" corners.

Don’t keep your ignorance, but your modesty. Some newcomers want this and that, and without this and that, it’s not a house. Everything must absolutely be included, but financially it’s not feasible at all.
140 sqm for 4 people is enough for 4 people if you give up a fireplace, dressing room, and huge pantry.

Thanks for the great tips! They really open our eyes. We will implement the tips over the next few days and try them out. If we now keep the 484 sqm plots in mind, are 28/29/30 the 'nicest' because they border the large 1000 sqm plot and therefore probably have fewer direct neighbors? Or which ones would you choose?
Many thanks for all the effort, we are very touched by so much honest help!

Are the 245€/sqm including development costs?
Because for us, that was another 100€/sqm on top.

You first need an overall plan.
600,000€ - 200,000€ for the plot leaves 400,000€.

Of that, 100,000€ for incidental building costs, garage, exterior facilities, kitchen, furniture...
That leaves 300,000€ for the house. That possibly results in just 120sqm without a basement.
Do you still want such an expensive plot then?

With a total budget of 600k, I would choose one of the smallest.

Thank you! Yes, it is developed and a heat pump is also installed on every plot. Good that you exist, that helps us a lot!

It is worth dealing with sound and propagation and driving to a similar area once. Usually, the houses directly standing at the noise barrier wall are not the ones that get the most noise. The noise level "sloshes" over the embankment, behind it it is surprisingly quiet at first (like in a wind shadow). The 2nd row of houses is the 2nd "wave breaker," that is probably where it is loudest, therefore. From the 4th row onwards, it gets significantly quieter.

I am unclear how you determined your space requirement in the house. Are 180 sqm an arbitrary classification or are there already planning considerations behind it that directly relate to your life?

I prefer to live with 4 people in well-designed 140 sqm rather than on little usable 180 sqm "status area." In this optimization, square floor plans (little usable area in the building center) are usually ruled out, although these floor plans offer the lowest price related to €/sqm.

So if you know your needs and the house, you can decide much better according to the plot location, here linked to the size.

Maybe this is a way out of being overwhelmed.

That was actually just a rough estimate. Friends of ours built 168 sqm and as laymen we find the house very well thought out and in our opinion every sqm is used. However, we would additionally like a second small bathroom for the children and thus came to 180 sqm.

One might think that you read a little selectively. ;) If you spend 200 K just on the land, there will probably be 130 to 140 m² house left. Is that enough? Once the land is bought, there is only a very expensive way back. But you give the impression that the idea of buying the land is being pursued a bit hastily.

Thank you... You are right. We really approached the matter quite naively, and you are helping us a lot right now!