What can be done with coils and what kind of basic knowledge do I need?
To use coils no preliminary knowledge is necessary. You build them, don't ask questions and use them temporarily.
If you work with them more seriously, a basic knowledge of coils as they are used in electrical engineering is indispensable. Their method of operating is the same: transform, change, translation of energy from one level to the other. This connecting requires prudence. You can connect your own energy and transform that, but also make higher energies available to Earth.