Hello,
1. How many minimum layer of board is required for MPC5775B controller?
This is not specified. So one I say.
2. NXP MPC5775B development board having how many layers in PCB and please provide the stack-up details.
Since we offer multiple evaluation boards, could you specify which one you are referring to?

3. Can we get the pcb or Gerber file for the BMS development board?
Yes, this is possible, in case you specify which one you looking for.
Best regards,
Peter