I know that Dreambox one has physically only 1 tuner inside but virtually 24 vtuner... How so?
Theoretically the only limit can be CPU/newtork. You can have n+1 vtuner but you can not use them all at the same time. How many you can use at the same time depends on the cpu and network speed.
When I compile new image, then also the drivers will be recompiled...? Or the drivers source code is closed?