To your first question, I don't get any slop when my Cannon rigger is screwed down tight. I use the same base that I believe you are using. My base is connected to a traxstech swivel base, which is seated to a track, so maybe that's why I don't get that slop. Not sure?
The noise you are hearing is normal. That's the positive ion control working. You'll notice it gets louder when the wind picks up. It can be annoying I know.