I may have destroyed my smartphone.
So how can I ensure that after installing the game on another phone I wont have to start at lvl1 again? 
If your account is linked to Facebook, then you’re safe, any other smartphone will be able to recreate that link.
I did link it, but honestly I never use the FB account for anything, since I dont use facebook.. at all. I dont even have a single friend lol
(I created the account only to link it to MPQ..)
Im really scared they will kick FB my account when I try to relink or something, thats just my luck 
Is there a backup plan, incase something goes wrong with facebook?
In a worst case scenario you can contact MPQ support and link your current devices ID number to your PVP name like they did for me when a new game started when I linked to Facebook.