I got a cast on my hand taken off yesterday, but I still can't make a fist. Is it permanently damaged?

Not necessarily. It is normal to have stiff joints after they have been in a cast. It usually takes time to get them moving again. This is especially true in the hand. If the stiffness does not get better over the next several days to weeks then ask your doctor.
No. Prob not. Hand therapy just as important as surgery.