PPL(H) theory credit towards PPL(A)
 

I have PPL(H). I want to take PPL(A). According to Commission Regulation (EU) No 1178/2011 3/11/2011 Appendix I 1.2 I must write exams on:
-Principles of Flight
-Operational Procedures
-Flight Performance and Planning
-Aircraft General Knowledge, Navigation

Question 1): Is there any difference between the navigation of an airplane and the navigation of a helicopter?
Question 2):Why the Navigation is not written in this law as a separate subject but is written as a secondary one added to the AGK?
Question 3): Is it written by accident or it is written reasonably in the law that an applicant for another category must write PoF, OP, FPP, AGK (ok for them) and Navigation exam too?

PPL(H) theory credit towards PPL(A)
 

Answer 1)
Things happen faster in a fixed wing, purely because of airspeed. Because of the faster speed, nav errors (off-track errors) are less in a fixed wing if dead reckoning. Conversely, in a rotary wing, you can pull up and have a think. Apart from those obvious little gems, nav is nav...

Answers 2 & 3)
No idea - these abbreviations mean nothing to me, I'm afraid. We don't use these in Oz.