Radio is coming on and off ie; won’t stay on. What could the problem be?

Tailights and dashlights not working all other lights are

So recently have a problem arise where when I am coming to a stop my car jolts/jumps when going from 3rd to 2nd in drive, when in manual gear select it doesn’t. Any ideas if it’s a stuffed gearbox or… 

I replaced my belt tensioner and now car won't start

My Amarok's acceleration become loose every time it reaches 80 what's the cause of that