Hi there,
I believe fuel consumption works the same way in MP as it does in SP, you can turn "Realistic fuel consumption" on and off in the settings (gameplay) of your game.
In terms of fixing your truck, you can either F7 + Enter which will take you direct to the nearest services (Please note that if you have a WoT contract, you will lose your load when doing this). Alternatively you can use /fix in the in game chat which will fix your truck there and then without having to teleport. (There is a cool down time with this function, I believe it is either 300 seconds/5 minutes or 600 seconds/10 minutes).
Managing your trucks, trailers and employees is the exact same as SP in MP, they will all work as normal.
The only major difference is that when your in MP, your sleeping time does not change unless you are teleporting from place to place. This means that you don't have to sleep every 11 hours in game.
I hope this helps you @WomenDriverzUnite