Baptism Records in Ireland are difficult, those records that survived are available on line:www.rootsireland.ie
A decent estimate of year born is a good start. You can do an All Ireland
search or restrict to Kilkenny.www.familysearch.org
has both England and Ireland after 1864:
Mary Ann Honeycombe born 9 March 1851, All Saints Church, Newcastle on Tyne parents:
Richard Honeycombe and mother Elizabeth
There are other Honeycombe's Cornwall and a Channel Is.(if you have a good idea of when she was born)www.freebmd.org.uk
did find Honeycombe quite a few John Doran's given a range of 1864-1874 for marriages
if you have census you might be able to find the right John Doran based on a census record if he married in England. The closest child born to marriage date may have a different place of birth and that may show you where the marriage took place.
Where did the marriage of Maria & Samuel take place? Usually a marriage record gives father's place of birth and occupation.
Did they have a son usually the irish tradition to to name first son after father or grandfather.
There were 256 Doran's in Kilkenny's Griffith Valuation in 1850 (John would of been 1 yr.) www.askaboutireland.ie
(this is where John's father's name might come in handy.
Far to many to speculate. There were no Honeycombe's in Ireland at the time of the Griffith Valuation and none in the directories of Ireland, nor 1901/1911 census, nor the Tithe records of 1823-1837.
I would say unlikely he met Mary Ann in Ireland.