It sounds as if there is a metal ring to hold a heat trap. I am going to suggest that you drill it out with a 7/8-inch hole saw, the same as you would a similar ring in the cold port that holds the dip tube. It probably won’t take more than 20 seconds. If the anode still won’t go in, post here again. A swap is a possibility, but I want to see what happens first.
As to the valve, I’m on less certain ground because I never did much soldering, but I’ve seen a fair amount done and I think, yes.