Well in one of the BTS videos I remember watching, someone (it may have been Bill Paxton?) saying how Cameron brought them all into a room with a table full of stuff to customize their armor/look with.
Drake definitely has some bones hanging from his neck when he wakes up from cryo, and he also has some dangling from his hat and his gun. I'm pretty sure Mark Rolston gets interviewed in that same part of the video and talks about it a little bit. I don't think he says anything about the characters mindset, but it definitely gives you a little bit of look into what his personality may have been like.
I can't remember the name of the video, but I'm pretty sure it's the same one where Michael Beihn mentions how much he hated the heart on his armor that Renner had added because it looked like a big bullseye to him