So now I have a Norton 4K/8k and a Shapton 12K(15k) on my way, with two shave-ready razors for practicing and also a Dovo Bismarck that should have been shave-ready, but in reality tugged a lot.
I thought I could use the 8K side on the Norton and the Shapton 12K to fix its edge, and just the Shapton 12K to refresh the two shave-ready razors.
So you're saying that, at least for now, I sound refresh their edge just on the 8K?
Depends how they were finished. 12k may be a good starting point if just refreshing.
What about the Dovo, should I go first to the 4K? Or to the King Deluxe 1K? (After learning with the practice razors, of course).
I couldn't say without seeing it but here is where you need to establish your own visual & kinaesthetic tests to assess edges pre honing.
Just bear in mind that the 12k Shapton is a very fast cutter.
Oh, speaking of the King hone , will it be detrimental to the razors mixing three brands like that?
Not in this case. They match up quite ok.