Elliot,
The orientation of the camera on the head has been discussed in various places. Personally I don't have any experience with working from either side, so can't comment authoritatively. If my memory serves right, I believe I read that the way the clamp is mounted now is advantageous for MF digital--something about clearance and tilt. At any rate, Hejnar drills the adapter in both directions so you can change the orientation to sideways, if that's what you like.
As for just attaching the RRS clamp to the Manfrotto QR plate, that will certainly work and that's what I was going to do until I emailed Hejnar. My feeling was that I wanted a solution that would be rock solid, clean, and would not add an additional chance for play. 2 QR plates together makes me feel a bit insecure. Also, since I didn't own an extra clamp, the choice was easy.
If you have any interest in a more elegant solution, you might want to email Chris and see if he will sell you just the adapter drilled out for the RRS clamp. He is very accommodating and fairly priced.
Paul