If I get into college and I want to major in CE but then change my mind and want to get into CS, how hard will that be to do?
It depends on the college. At my school, all of the majors are open to anyone who wants them, but that’s not true at a lot of places.
Depends on the college. You should consult your department head or advisor and see what you need to do in order to change majors. I went from an East Asian Studies major to a Japanese major and it was easy since I already had most of the requirements for the Japanese major fulfilled (since a lot of classes for EAS and Japanese overlap with each other)