1. our school used the jacplus business management (key concepts) text book, not sure if they really differ that much, to be honest our school hardly used this book (we occasionally did some questions from it and sourced a few definitions from it) but our teacher basically supplied us with lectures of notes, that he recommended we use.
2. Personally, i found that shinny's notes where good in most areas and supplied me personally with insight, however parts of the notes are dated (lack current examples) and have things that aren't referred to in the current study design.
3. Business management i found was broken up into two sections, ovbisouly the exam and the sacs, personally i think that you should attempt to incorporate the information your teacher has specifically taught you in the sacs (as they will be the ones marking them). In our cohort, the students who ignored the teachers notes and attempted to use lecture notes/ checkpoints struggled in some sacs. For the exam however i recommend you com are your own notes with that of checkpoints, as it will add clarity in some areas
4. Difficult to discuss potential scoring without knowing all the facts but, there have been people who have scored 190-195 out of 200 for sacs and have scored 50, basically if your receiving 95% and your cohort is strong, anything is possible with a perfect score on the exam
Hope this helps, Pm me if you have any more questions regarding this subject