Does lidocaine have any effect on psvt and af due to Wolff-Parkinson-White (wpw) syndrome?

Yes. It along with Procainamide are therapy of choice. The typical agents i.E adenosine, verapamil etc are not good as the can block conduction through the av node and allow rapid conduction through the accessory path and lead to hemodynamic collapse.
Rarely. It is usually quite safe to use, but also will not improve symptoms much except in a few cases.