Thx again for taking the time to answer this thoroughly.
I spent most of the last days reading on various topics (client prediction, server authority, substepping, PID controller, interpolating) and I think I just delved into an too ambitious project as a total newbie in everything related to creating games.
I think the pre-applying of some variables would be a nice solution indeed. But trying some things in that direction made my head spin. I actually implemented Bored Engineer’s MMT plugin and it seems to do just exactly the things I need. Now I can apply forces and torque without worrying about different outcomes. Tried to implement substep on my own - but no way without cpp knowledge 
Thanks again for taking your time - though I hope I did understand the concept behind it - implementing those is another story