Congrats on the new .416! You're going to love it!
In regard to slicking up the bolt, with the .458 that I have, I slathered up the bolt with JB bore paste, and worked it about a thousand cycles. It does a wonderful job, producing what is now the slickest bolt in my collection. One word of caution however, do not turn the bolt into the locked battery position. That would lap the locking lug surfaces, and therefore increase the headspace. Just cycle the bolt fore and aft without turning it down. Give it a good flushing with some sort of crud cutter afterward to get all of the paste out, and you're good to go!
I would recommend a proper glass bedding job, even with the new dual crossbolts, and by the way, if your sights don't regulate, you can order different front inserts from CZ-USA. I had to order the tallest front that they offer, which still wasn't quite high enough, so for me, it's time to start filing down the rear leaves.
Again, congratulations, and I hope that you truly enjoy your new big bore!