Trying to optimize my hangar

Hi pilots

I'm trying to make my current hangar more competitive in its current tier. No idea what tier I'm in, though. I only know it's fun and I wanna stay there. I'm fairly new in the game and have raced up to lvl 29 in about two months. So there's still tons of stuff to learn for me. My hangar is probably not the best solution for my tier, but they are my favorite bots and I have no intentions to swap them out. Here's the deal...

Gareth 6, Taran 7, Magnum 7
Rogatka 6, 2x Punisher-T 7
Vityaz 6, Thunder 8, 2x Punisher 8
Galahad 6, Taran 6, 2x Magnum 6

What tier am I in and how far can I upgrade? Since I got 3 AU bots and some WSP weapons, I'm not sure what to do. I know about penalties but have no deeper insight yet. It would be cool if someone could look over my hangar and tell me what can be optimized. Is my Vityaz allowed to be leveled higher than the other bots. Or Gareth since it's a light bot? How far can I upgrade Galahad without getting pushed into higher tiers?

Lots of questions, but good advice is much appreciated