Merchants, along with other player characters, are the primary source of buying and selling goods within Appalachia. No non-player character merchant is human with most being protectrons. They can neither be engaged in combat nor harmed.
Vendors' inventory are server based. Switching to another server will show different inventory.
Each vendor has 200 caps when reset.
The available caps each vendor has access to is player based. Switching to another server will not show a different amount of available caps.
Vendors' available caps are internally shared among the faction. For example, if you sell stuff to the Raider vendor bot at Sunnytop Station and he has 5 caps left, then go to sell things to the Raider vendor bot at R&G Station, he too will only have 5 caps to give you.
The reset time is approximately 20 real life hours from when you last traded with them. For example, if you traded with them at 4pm, it will reset at 12pm the next day.
Vendors' inventory is not internally shared among the faction. Vendors of the same faction will have different inventory.