Hey Charaa
The
Weapon Limitations Guide says that you can have 8 on-Tier weapons and 2 Tier-Equivalent Weapon Groups.
You can go up one Tier by 'spending' two weapons, or gain one weapon (1->2) by going down a Tier.
You've got two Tiers listed on the Night Star - Tier 12 for its size and Tier 8 for its shields. A corvette is usually on the smaller side, but I think Tier 8 is probably too small for that. Tier 10 is probably a good size for a Corvette and would better match the description you've provided. Your length seems about right for a Tier 11/12. You can find more info and examples
here.
For vehicles, there's no 'hard' rules around it. What I usually do is figure out how large of a space I want to dedicate to a...