yep, Every alt of both factions, from every server, is in your Warband automatically. You can pick 4 to be your favorites, so they’ll show on your home screen together, but that has no impact on gameplay. Your main character is just whoever you feel like it should be that day. I think all the quests and rep unlock for all characters together, [so you won’t have to repeat a quest on a different character if you don’t want to ← I’m less sure about how that part works.]