This is all so interesting to me hahahMy guess is that the USA royal watchers will be less interested. Now King Charles III isn't nearly as popular as was Queen Elizabeth II
Nope, straight down to first born, sideways only if there is no child. That is how Elizabeth's father, King George VI got the throne when his brother King Edward VIII abdicated to marry Wallis Simpson, a divorced American commoner. Quite the scandal.
As you saw in the chart, Queen Elizabeth's siblings Andrew, Edward and Anne, along with their children, and Harry and his children are "nothing" with regard to succession when King Charles dies.