Prendergast Family

I am looking for as much information as possible about my ancestors, the Prendergasts. My great grandfather, Patrick was born in 1851 in Kilkenny County and his wife, Julia (Hayden) born in 1871. He was a farmer and they lived in Kilmackshane, Ballyvool, Kilkenny in 1901 and 1911. They had five children, William, Margaret, Nicholas, John and Peter. William, the oldest and my grandfather, was born in 1896 and emigrated to the United States on the SS Philadelphia when he was 19 years old in 1915. Margaret and Nicholas never married. John did marry but I do not know to whom. And I believe Peter became a priest. I believe my great grandfather's name is William but this is the only information I know about him. I would love to know more about William, my great-great grandfather, and Patrick my great grandfather. I am doing a lot of research on my own but any help I can get from this post is welcomed and appreciated!

With respect to Julia Hayden, I would love to know as much about her family as possible. I believe her family is from Kilkenny County. I believe her father's name was Nicholas Hayden but this is all I know about him. I do not know whom he married and whether that had other children than Julia. I am reasearching the Hayden's  as I post this message looking at civil and parish records from 1800 to 1850 as well as other documents. I also know Julia emigrated to the United Stated some time between 1911 and 1944, because she passed away in 1944 in New York, New York. William, her oldest son and my grandfather, passed away in 1948 in Jersey City, New Jersey.

Many thanks for any and all help that may come my way!