Adding another texture to a clothing item

  1. Good guide to share is this, it’s slightly outdated but will get you started on the subject and you can seek more specific help for any issues later
  2. It depends, but generally you will need to physically cross-match the clothing items you are trying to replace in the GTAV files using OpenIV or the CodeWalker RPF explorer tool. It’s a super tedious process and I’m not aware of any methods of significant automation there, if there are any