Hi Eric,
Thought you'd be interested, based on postings we did some 8 or so months ago. Sorry I was so slow to post back.
It's just a metric hex wrench AKA allen key/wrench. Pretty sure it's 3.5mm which can be a little hard to find in N. America, but a good hardware store will have one.
I used just the right amount of force to remove the Arca ;)
Actually it didn't require any excessive force at all. Just about what I expected. No sign of lock-tite. It is a stainless screw threaded into aluminum, so it's not going to be over-tight due to the danger of stretching the threads. And that's a good thing to remember when putting the RRS on: don't over-tighten. It's a somewhat shallow set of threads that are engaged.
There is an anti-rotate pin in the D4 top pan that will fit into a large recess in the B2 LRII, and if you rotate the new clamp counter-clockwise until it stops before tightening, it will do it's job of preventing any possible rotation of clamp on the base that could lead to loosening.
Go ahead and do it! You've been wanting to for a long time.