Ok I did some test about the pit problem.
I did the following: 1 Lap Multiplayer Race with 1 AI. As soon as the green light goes on i press shift+s to go to the pit menu and then I rejoin after the 12 seconds (I really think the Ok button in the put should display the countdown, too). Directly after exiting the pit i mae a short pit stop and continued driving.
The result was, that the AI got a 30 seconds penalty for "compulsatory pit stop too late" (well in 1 lap...

) and at the end a disqualification for not pitting. I however got the 30 seconds penalty for pitting too late and won the race crossing the line as second because i did a stop at the beginning but in the F12 menu there is still the red "yes". (see screenshot)
So my conclusion is:
- Add countdown to OK button in pit
- If you stop at the beginning you only get 30 seconds penalty for pitting too late but no disqualification for not pitting. => disable pitting x seconds after leaving pits
- automatic disable compulsatory pitting if race length is 1 lap (DRAG!

)