Welcome to TorqueCars. :bigsmile:
Plenty of ideas, dynamat for noise reduction, used for lining the car when upping the in-car sound system.
For comfort get some seats from another car, Audi, Merc etc and adapt the runners.
Safety, how far do you want to go? Bull bars, roll bars? Harnesses?
Performance, start with the basics and improve the breathing via an improved exhaust and induction system, I'm sure there are some tuners out there as I have seen some offroad Niva's.