At the moment, there doesn't appear to be a vanity feature for retainers. It existed in 1.0 though and I'm sure they'll bring it back sooner or later. For now, they're stuck in that airplane flight attendant looking gear >.>
As per the original question, yes. The customization is a 1 time deal. You hire a retainer and then customize their appearance, choose personality, and name them (the old 1.0 name will come up during a prompt at the end if you had a 1.0 retainer, allowing you to keep the name or change it). After you finish, you'll be able to access any items from 1.0 that were left in your original retainer(s).
The customization is pretty sweet though. It's identical to the regular character creator, except it doesn't force you to leave the game or anything. It's built right in
As per the original question, yes. The customization is a 1 time deal. You hire a retainer and then customize their appearance, choose personality, and name them (the old 1.0 name will come up during a prompt at the end if you had a 1.0 retainer, allowing you to keep the name or change it). After you finish, you'll be able to access any items from 1.0 that were left in your original retainer(s).
The customization is pretty sweet though. It's identical to the regular character creator, except it doesn't force you to leave the game or anything. It's built right in
