Rear Bumper
 

Before I purchased my car, the rear bumper was replaced. I dont know if there is suppose to be a but i have little free play and movement on both the left and right side of the bumper at the wheel well and just below the license plate bracket. Should there be a lilttle movement or no? And is there a special tool you use to remove those plascit bolts, cause I'm almost afraid to take them out without breaking them. Is it possible to drill out those holes and replace them with real bolts, or would that cause an even bigger problem?

Thank you for any advice or help you can provide!