During my undergrad I was friendly with most of our grad students in AH and found that most of them had minimal experience with AH during their undergrad. Experiencing anything in the field rather than in a classroom speaks volumes, so I wouldn't worry about that aspect.
For the reading, I wouldn't stress too much. I think you should read what interests you and gets you excited about art. There are going to be many nights in the future where you sit wondering why you're torturing yourself with theory books.
I definitely understand your concern about how focused SOP's should be, I'm terrified of being too specific and alienating myself.