[TeaLeaf]

I think buggies do have a role. They need to cost about as much as 3 or 4 flashes and be cheaper than the skyguard while having similar firepower (but less armour). That gives them a role as both light attack vehicles and cost-effective group transport.

Don't bother with common-pool, just have the 3 faction ones:

NC
1 Driver, 1 Main Gunner (360 degree heavy turret), 1 Front Gunner (160 degree light turret).
Decent armour, can survive at least one AT weapon hit.
Slowest buggy.

TR
1 Driver, 1 Main Gunner (360 degree heavy turret), 1 Front Gunner and 1 Rear Gunner (160 degree light turrets)
Fast but fairly fragile.

VS
1 Driver, 1 Main Gunner (360 degree heavy turret), 1 Front Gunner (270 degree light turret).
Is a hover vehicle so can strafe etc.
Armour and speed somewhere between NC and TR.

All buggies should start with a Heavy AI weapon as the main gun but be able to replace their Main Gunner position with:
Variety of specialised weapons
4 slot open topped transport area that passengers can fire from
Resupply station
Stealth field
Advanced sensors
...and stuff like that

You should also be able to replace the front (and rear) gunner weapon, but only with anti-ground weapons, as it likely won't be effective as an AA anyway due to limited firing arc.

I think tying the buggy certs to infantry classes is a little weird though, just let people take what they like.