You missed out Birch and Bramson, the original manual.
presumably instructing reading up on exercises before flying them, then just using the brief as a recap and Q&A session.
No, these books are useful preparation for the student, but only that. You the instructor should give a full pre-flight brief on the exercise to be taught together with a check of understanding, them teach them what you have briefed. The books were written to sell books not to teach students how to fly. The end product is only as good as the preparation.
Whether the preparitory material is in book or electronic format makes little or no difference, the idea is that the student comes prepared for the next exercise so that you don't have to go off at a tangent and teach them lots of additional theory. The PPL theoretical training is now so far removed from the flying that it can generally be regarded as useless and represents nothing more than another obstacle in the licencing process.
As for which one, they are all much of a muchness largely copied from the same source.
This one is much better