If you are asking from the examination point of view then let me assure you that you do not need to learn them at all. There's no chance that PMI will gauge a candidate on his ability to mug up something. Focus more on Integration processes and their ITTO and try to develop understanding of unique one from other process. Again, no need to mug them all.
EEFs is the environment in which company operates that may limit or enhance its ability to execute a project. OPA's are kind of intellectual property of organization acquired over the years from earlier experiences.