Appointment with Planning Office - Preparation

Do you have any tips on what we should place great importance on regarding planning?
Are there specific things that definitely must/should be included in the planning contract?
As a layperson, can I even tell if a planner is "reputable" or not?
How do I protect myself against massive budget overruns?
Is a corresponding contract mandatory, or does a planner just start on a "handshake" basis?

Just try using the search function here. If you search with "from: 11ant" for the terms Einzelvergabe, Eigenvergabe, Zauberlehrling and Gerddieter, you should find what you need.

The planning office was recommended to us by acquaintances who have already worked with him, but in the multi-family house/commercial sector. I will ask for single-family house references.

Apartment building planners can usually stick quite well to the budget, but mostly under the condition that you do not tend towards an "extra sausage" specification of construction services.

The main risk area with own work lies in coordinating it with the workflows of the other trades, in work-on-account hours, and in the warranty regarding trades that follow. But most of the "learning money" is wasted by the apprentice builder in the tendering and awarding process. Second place in the error hit list is to commission a planner only up to the building permit stamp (and that is mainly punished with drywall bumps).

This could certainly lead to misunderstandings! Already a very good hint, I will emphasize this clearly in the conversation and probably will not hand over the detailed drawings either.

But feel free to post them here. Every floor plan, every drawing is welcome here and "evaluated".