Those are really great peppers and whatever you are doing, keep doing it. I don't see any disease or really any pest problems.
My peppers especially the tobasco can live for several years, but I get pests, and fungal issues. I do top the tabasco to cut off diseased leaves and also to keep them shorter and bushier. I top some of the others because when they get older, it helps to rejuvenate them. Except for tobasco and super chilies most of the other chilies don't live more than a couple of years and many of them are annuals.
I am envious of your bell peppers, I have a hard time getting them over three feet and I am lucky if I get 5 peppers before they die.