Civil registration did not begin in Ireland until 1864 so before this all births, marriages and deaths were recorded by the local parish priest so this is where you would have to look for the children's? birth records. Unfortunately, sometimes it can be difficult to get Catholic records that date back so early and this is the case with records in Donaghedy parish where records do not begin until 1854:
http://www.irishtimes.com/ancestor/fuses/rcparishmaps/index.cfm?fuseaction=showidrecords&CityCounty=Tyrone&parish=Donaghedy&churchid=361
It may be a good idea to contact the Irish World Heritage Centre in Tyrone to see if they can offer any assistance or advice. Here is their email:
info@irish-world.com
With regards to ship records you best bet is to look at the port of arrival. For information on US immigration records check the National Archives at http://www.archives.gov/research/immigration/
Another good website for information on passenger ship records is http://www.irish-genealogy-toolkit.com/US-immigration-records.html
Here are some other websites that you may find helpful:
The National Archives of Ireland http://www.nationalarchives.ie/genealogy1/genealogy-records/introduction/
The National Library of Ireland http://www.nli.ie/en/family-history-introduction.aspx
The National Archives UK ? genealogy search: http://www.nationalarchives.gov.uk/records/looking-for-person/
The Public Records Office of Northern Ireland http://www.proni.gov.uk/index/family_history.htm
The Ships List: http://www.theshipslist.com/index.html
Family Search: https://www.familysearch.org/learn/wiki/en/Ireland_Genealogy_Websites?goback=.gde_3030105_member_230205486#Emigration_Records_.2FPassenger_Lists
Genealogy Links: http://www.genealogylinks.net/uk/ireland/tyrone/index.html
I hope that some of these links are helpful. Please be patient - as our programme has only begun to rollout across the island of Ireland and volunteers in some areas may not yet be organized.
Kind regards,
Genealogy Support