Under JAR a PPL(H) can obtain a FI rating but they do have to first pass the CPL theory (As Muffin said) A PPL(H)/FI can give flight instruction for a licence but only for a PPL(H) or type ratings. A PPL(H)/FI can’t be paid for flight instruction but he can be paid for ground instruction or other non flying services.
You need to at least hold the licence or a higher licence for the instruction you’re giving, so a PPL(H)/FI can’t give instruction for the grant of a CPL(H)
SPIC or Student Pilot in Command is time when the FI is on board but does not influence the controls, SPIC can be logged in place of PIC for some professional integrated licence courses, for instance fo a intergrated CPL(H) you need 35 hours PIC but 15 hours of this can be SPIC.