The rear post mount is some kind of coated magnesium not carbon. Caliper bolts need to be tight so the caliper doesn't move, put loctite on them.
I don't think the tape that comes with it is matt finish either?...mine wasn't.
Get some self-amalgamating tape to put under the chainstay protector and maybe put some on the seatstays.
Hope you get it built up soon, I'm full of cold so can't get out...taking mine to Morocco in a week or two though, wish it was a 160 for that!
Edit - the rear caliper mounts directly if you're using a 160/165 rotor. I had to use a post to post mount for using a Formula 185. It's still looks tidy and is a lot better than an IS mount.