[Chacal]

Autochton : Using it as a moving barricade is historical, but i'm not sure it's the only way I will do it. For now I have constructed 2 wagons. One will work as you give the example, a defensive way, not moving, firing a lot of crossbow shots. The other one will rather move to contact of the enemy.

I'm now decided to use the multiple 10hp forms. It works well and is more fun.

The mapmove is 2 to let it go with most infantry armies.

I will maybe give it the fire vulnerability mostly for fun and to give it a vulnerability, even if IMO, a wood wagon would probably not burn so easly.

As for the resource gold cost :
The resource cost of the Crossbow WarWagon would be those of 3 crossbow, 1 Spear, 4 armors and helmets, plus a cost for the WarWagon itself. I'll have to decide about the gold cost too.