First of all, civil registration of births in Ireland began 1864 and not all early births were actually registered since it wasn't compulsory until 1870. One of the best places to search for Irish births 1864-c1882 (although not complete) is IGI at
www.familysearch.org.
To get a more exact date for the marriage (1895-1900) you would probably need to search through the indexes (which are not available online as in England and other places).
I also have my ggrandmothers death certificate: Margaret PHELAN (nee Bergin) D. 29 August 1879 at Sragh (born 1832). Husband Kyran PHELAN. Same question about birth certificate and marriage (around 1840). Thanks. Jim
There will be no birth certificate for Margaret & husband if they were born that early. Their marriage certificate will probably be available as civil registration of Catholic marriages began 1864 (Protestant marriages from 1845).
There might be some information online and I would first suggest checking on LDS site, then put something like 'Kilkenny records' into Google and go through anything that comes up that looks promising.
The best information will probably come from church records (if they exist for the period you need). Since you are fortunate enough to have a place you can chek LDS catalogue (follow the links to library catalogue & do a place search) to see what records might have been microfilmed. If something is there you can order the film from your local LDS library for a small fee and view the film there.