Get a Battery Eliminator Circuit (BEC). You can Google it.
You'll need a substantial DC-DC converter for that, you might be peaking anywhere upto20 or 30A.Your teacher needs to go back to school !!For servos I'd have chosen LiFePO4 2S battery pack, which at 6.6V would be much less likely toblow up servos. Or have looked for higher voltage servos, but that would perhaps get expensive.
You can do that. Use a few regulators. Power a few servos with each. Not a problem.
You might need to do a little redesigning of the circuits.This is what I would use:HobbyKing 20A BEC