Do they spawn extra on caravan plunder? not sure, I take very careful precautions with caravans in this version.Again about version 3.0.4. Didn't see any changes about it.
Can barbarians buy units? It is the barbarians, not the camps.
A camp appeared and the barbarian was in the way of our caravan. The caravan was looted.
This is the first time I've seen a second barbarian appear nearby, which is in an inactive phase. This barbarian stands far from the camp, that is, the camp could not buy him.