We chose the 50,000 contract, which is sufficient for TV in HD plus simultaneous internet surfing. For the SAT, do not install the dish on the roof, but rather at [B.] on the carport roof or similar. This makes changing the LNB a breeze.
Yep, it is. I had to resort to a router cascade and separate the networks:
Internet connection -> Fritzbox -> Telekom receiver, Gigaset Go Box and Sunny Home Manager -> Dreammachine Pro -> Switch rest of the house wiring.
There was no other way.
So we decided on a dish on the roof for TV reception. I can access the LNB directly through the large skylight without having to go onto the roof. I waited for the internet connection until the municipal utilities had laid the fiber optic into our house. It's been running at 100 Mbit/s since August. Since we were in the funding area, the connection was free for us. Saved 1800 euros. :)