Walsh - Heffernan

My ancestors emigrated from Kilbehenny, Ireland to New York around 1850. I would like to find the exact date they left Ireland and determine if there are current descendants of the Walsh (currently Welch) or Heffernan Patrick Welch 16 Jul 1790 Ireland Wife Margaret Heffernan (1795) Children Daughter Bridget Toole(1823) abt 1823 Kilbehenny, Limerick, Ireland Birth of Son Michael Walsh(18251906) 11 Sep 1825 Kilbehenny, Limerick, Ireland Birth of Son Patrick Welch(1828) 13 Apr 1828 Kilbehenny, Limerick, Ireland Birth of Daughter Mary Walsh(1832) 30 MAy 1832 Ireland Birth of Daughter Catherine Walsh(1834) 1834 Kilbehenny, Limerick, Ireland Birth of Son John P Welch(18381918) abt 1838 Kilbehenny, Limerick, Ireland Birth of Son Thomas Welch(1839) 03 Feb 1839 Ireland Birth of Son James Welch(1843) 10 Jul 1843 Ireland