Hmm... I have a bit of a plan for keeping Magic secret, while telling Danny about our powers. The basic idea is to keep Excalibur secret or make it out to be a Master power construct, while having the Magic be a complex power that allows for precise energy shaping with the visual spell circles being part of the energy-focusing mechanism. Basically, describe the Magic in Parahuman terms as much as possible. The thing is that Taylor doesn't know enough about magic to make it work out effectively. So, my vote is as follows:
[x] No, you don't
[x] Magic theory
-[x] Focusing on the nature of magic itself, the groundwork of how it functions, rather than spell-creation theory.
Edit: This way, we start on the path to being able to make our own spells and possibly get started on learning how to teach magic and create Devices, basically working on learning the foundation of magic-as-science that Nanoha's setting has so that we can get to the point of having a decent shot at dealing with Scion without going full Kephri.
Alternatively, it's starting the groundwork for staying sane through going full Kephri, allowing us to unleash magic able to let us actually fight Scion directly, with magic-user backup for the Kephri people control to use for combination spells.