Is the Qu'ran a Furqan or is it a separate book revealed to Musa(pbuh) and Haroon (pbuh)? 

T. J. Irving: The month of Ramadan is when the Quran was sent down as guidance for mankind, and with explanations for guidance, and as a Standard. 

Furqan is another name given to the Qur'an; very much like one of its functions, to be used as a standard for judging between right and wrong, amongst other functions, i.e. being a healing, a reminder, a guidance etc.