Please provide guidelines on Functional Specification

Hello Everyone,

I need to know about Functional Specification and Reports for sub modules like PA and OM.

Is it compulsory to have ABAP knowledge for performing role in Functional Specification. Does a functional consultant creates user exits, and does Testing. If yes, how?? Please help me out with this. Any input from anyone would be a great help for me. Thanks in advance.

Rachna.