Hi JILogan, to answer you short: for flight-seeing you need a CPL and 13 CPL theory exams (instead of 14 for ATPL).
Without CPL theory(13 exams) you can teach only towards LAPL (I'm afraid no other ratings), but you need also to convert at least your PPL (9 theory exams) and FI into EASA one.
Best advice: contact schools in Spain where you'd like to teach/fly and they might be able to assist you for whole conversion process.
For acronyms and other reg explanations read
https://www.easa.europa.eu/system/fi...u/Part-FCL.pdf it's a 'FAR' for EASA world.
Good luck!