if you are using android, try "clear data" first. it will erase all the data in the google play account also,
no, that doesn't work with T11.
Only if you leave the game for a very long time as @JC3.

I clean data (or install-uninstall the game) very often so to be able to collect more easy boosters but my fb is always connected with my team.
Only if start a team with a new fb or google account.

but I agree with @ adifairus
If you built a good team and secured the CH.L. for next season, keep it up.
Sacrifice one expensive player to avoid bankrupt.