Have you read my posting on this message board :"ORIGIN of the GUINAN clan". It will give you some information regarding your name.
Queenstown,Co. Cork is the port from which most of the emigrants sailed to Ellis Island. Maybe this is why Co. Cork appears in your family story. Were Bernard and Francis Guinan born in the US or did they emigrate from Ireland? If their father emigrated from Ireland then they may have travelled to the US via Ellis Is. The records there go back to c. 1895. Worth a look - but you can expect to have to search for other variant spellings of the name (see my other posting)