Saint Brendan the Navigator
Saint Brendan the Navigator is considered the patron saint of geography. He was an Irish monk and sailor known for his legendary travels around the Atlantic Ocean, which inspired many geographers and explorers.
No, Irish is not the name of a saint.
Siobhan is a feminine Irish name. There is no evidence to suggest that there is, or ever was, a Saint named Siobhan.
There is a Rebecca, a matriarch from the Old Testament and there is a Saint Rebecca the Martyr who was martyred in the 3rd century in Alexandria, Egypt. Then there is St. Rafqa, sometimes called Rebecca, from Lebanon. None are from Ireland.
Saint Brendan the Navigator died about the year 577 at Annaghdown (Enach Duin).
There is no saint named Niamh. She is a mythical Irish character.
Patrick brought Christianity to the Irish.
I imagine you are talking about (Brother) Saint Brendan. He was an Irish saint. His name means 'Prince' in Welsh. He is known for among other things, his Voyage across the Atlantic. http://en.wikipedia.org/wiki/Brendan - In Irish he is called 'Naomh Breandàn'
Saint Cinnia was an Irish princess who was converted by Saint Patrick.
Saint Patrick is the best known of the Irish saints.
Saint Brendan
No but it is a variation of Mary