I had, I believe, 5 layers, but perhaps 6 or maybe even 7; I had a couple little things that I wanted to work out before going into Photoshop and made a few quick final layers and don't quite remember. It was not 10 for sure, even though the latest update to 8.1 (which I am using) increased up to, what, 16 I think.
I'm on Windows 8.1. Love C1 generally, but there are a lot of little things that bite me in the ass and it's pissing me off quite honestly.