How does deconstructing vehicles work

Your weapons will be locked if you continue friendly fire. This can be between 1 and 30 minutes, however, you will not know how close you are to having your weapons locked. The only way you can tell you're getting closer to that moment are the messages. After several messages, you will have your weapons locked.

As far as i know, there are no other punishments.

This is not a complete answer; however, I have managed to dig up solid information about the tanks here. I still have very little information regarding MAX's, beyond this chart which details their anti-infantry weapons.

To expand on this answer I've found relevant information about tanks. Tanks actually take (default) 50% damage on top and sides, 45% on the front (38% for Vanguards), and 120% to the rear. The armor plating defensive items add onto this, so for example the 5% damage resistance on frontal plating reduces damage to 40% (roughly twice as good as it says on the box). In all cases this results in an increase to the hits-to-kill of one (or two for prowlers, more for Lightning 75mm gun)