New players constantly spam GS and suicide them

GS is very easy to feed enemy team with. Also I generally find that having a GS player on your team just makes the enemy spam AA, which makes Air's job misery.

I agree, maybe gunships should be able to turn really fast (as helicopters do), and maybe have some firepower which they do not have...

Eh yeah...
Gs are on the verge of overstrength!
They have one of the best raiders, can counter every strider, have a high range tanky riot/assault, they have two of the best "burst dmg" units. Oh and they have better anti air then air itself.
What more could you ever need?

Unfortunatly I don´t know how to solve the "noob goes gs" problem.
The only thing I often try is to simply tell them to switch.

Oh, I thought of one other weakness of gunships, they can't fight underwater stuff.

Still though...

The problem isn't with the gunship units. The problem lies with the massive player densities that you're playing in. When you merely need to pay attention to less than a stinger's worth of map width/height, you're bound to run into problems with unit interaction.