I am unable to answer your first question.
With regard to your second question, the reason that you cannot find the theoretical knowledge requirements for the holder of a CPL(H)/IR to ATPL(H) is that an ATPL(H) can be issued without an IR(H). It is my opinion that, if you have to retake any exams it will be all the ATPL(H) subjects less Air Law, P of F (H) and VFR Communications.