Hi @HERTOGS Alexandre (EXT) GbsuCldDit , welcome to Microsoft Q&A forum.
Thanks for providing such a detailed analysis an yes you are correct in mentioning that some code piece could still be corrected with respect to v4 and as there is lot of documentation available already, the internal team keeps on updating them as and when we notice or someone points out.
The link provided above is a good start if you want to rewrite code and has a very clear and detailed description of implementing basic code scenarios. If you face any trouble with them, we would be delighted to help you out on the same. Below are some more article you can refer to, you can start with Main method.
- https://video2.skills-academy.com/en-us/azure/cosmos-db/create-sql-api-dotnet-v4
- https://github.com/Azure-Samples/cosmos-dotnet-v4-getting-started
Again, we appreciate your efforts for feedback.