Good morning my name is XXXXX XXXXX I will assist you today.
The screws are not needed. they were installed to keep the rotors secure while going down the assembly line when the car was manufactured. After that time, you can discard them as the wheel will hold them secure.
As far as the pads, the one plate is already installed and not needed to add. The hardware kit you got contained the plate that was already secured to the new pad. It is a anti squeel kit provided for noisy brakes.
So, Are you telling me that the two plates, solid and holed are not required on the new pads, because the plate is already attached to the new pad?
In my opinion, I install them out of the box as they are. the hardware kit is for someone who is complaining of noise and the pads, usually aftermarket do not contain the plate to keep the pads stable in the mount.