I had an over under system but sold the bike I was using the faceplate with. Hell, if you are interested in an over/under 26.0 faceplate and a set of armrests, give me a holler.
But to answer you questions:
1. yup face clamp size
2. I've ridden without pads and its okay for 10 minutes at a time, but I went with the armrests myself
3. I liked the system while I had it. It's fairly light, the armrests sit low, and it's fairly easy to install