I've changed all mine - on a LHD car though.. Think should be same way to do it anyway...
Do you have 1 or 2 flap motors sitting there? Mine got 2 but cars from may 2007 and onwards should only have 1.
Not sure, but mine only didn't have any screws there? Only taps and then a piece og plastic that clicks in over the motors and holds the motors in place.