I think many of us wish we had our old model collections back. I got rid of all my built cars and trucks when I was 18 but started back building at 23.
I still use Testors orange tube glue for models. Its been around forever and will not haze glass over like most super glue. I have used it 41 years now...
I have painted models with and without primer. Prime will fill small scratches and give paint something to hold on to. The best primer for models is Tamiya fine surface primer you can get at Hobby Lobby.