Surface of the glass must be thoroughly cleaned and degreased with example industrial alcohol prior to attaching the holder. Firstly, place the suction pad on the glass, and then turn the lock ring clockwise until it stops. If the suction pad has been clogged with dust, it can be easily washed with lukewarm water. Then let it dry in the air.
No, the magnets used in phone holders are not strong enough to have a bad effect on the phone.
If the plate is not placed directly on the spot where the wireless charging coil is, it should not have any bad impact on the functionality.
In this case, it is not possible to guarantee the phone will hold on a magnetic holder properly. For attaching the phone, we recommend using the metal plates that are included in the package.