You will be only hostile if you faction flag or red flag(pk mode) other than that you will be fine, and yes it works on every server just don't forget to check prices
I don't understand why you walk to Caerleon instead of just teleporting there, buying materials from the market, and then crafting. There are plenty of NPCs available for T8 crafting in Caerleon city.
1) Prices for material are high in careleon 2) Royal cities have specific bonuses to certain gear to craft ( in this example we get 24.8 % resources return on plate helmets) 3) I'm playing on New character
