go to settings- advanced features-motions and gestures-lift to awake-turn on ..yet there are third party apps on playstore but I am against those.I only use them on a great need .. good luck brother 

due to no notification light I suggest you to turn on tap to wake option( I did this on my A50)..or else flash notification yet this option blink your flash light on irritating way in my opinion.. good luck

can't understand your question brother

download ssecure app from playstore,,open it , click on lock and musk app - choose apps which you want to lock- done

i have the same question , i am a A50 user btw.