How to play Wagon in 1st Age

Hello, I have some difficults with using wagons in my army.

As mentioned at page 121 1st Age book there are no detailed rules (core system) for vehicles, but looks like some moments need clarification:

1) as I understand I can buy wagon as addition to any squad which have access to it (via Vehicles of War for ex), and it will be treated as part of squad (I have to maintain 2" coherency with it, it activates simultaneously with all squad, etc). Is it correct?

2) I see characteristic "Transport 6" in the profile, but does not see description, is it mean that I can say that up to 6 models from unit are inside wagon (embarked) and remove it from the table until I like to move models out of wagon? Or I just place all models together as squad and add bonuses to Combat Situation (if wagon provide any)?

3) At page 120 "Drivers, mounts, and vehicles and be targeted by the enemy individually", but what about other models of the squad (passengers)? Wagon upgrade "Wagon Canopy" provide Cover 2 for driver and passengers - does it means that passengers may be targeted individually too?

3) If I have Ballista on the wagon, wagon Toughness is 7, Ballista is Strength 8, does it means that Ballista count as Heavy weapon for wagon, I can move it up to 1*Movement and fire, and in such situation I do not need 3 Crew for shooting as mentioned in Ballista profile?

4) One model called "driver" in my squad may do actions as other models, or it drive wagon and cannot do anything?

Example: I have 3 human models in the wagon, human have muskets, wagon have ballista, when I use action and try do maximum shooting:

I can shoot 3 times with musket and 1 time with ballista /or/

I can shoot 2 times with musket and 1 time with ballista (because driver must do anything while driving) /or/

I can shoot only with ballista (because it have Crew 3) /or/

I cannot shoot with ballista (because driver can do nothing while drive) and can shoot 2 times with muskets

Thx in advance