http://wicklow.rootsireland.ie/quis.php?page=1&confirmPageView=YAs far as I can find out this is James marriage cert (no guarantees, as they wont let you look at them without paying) but the date ties in roughly with the age of Gertrude.
If you register, and then go county by county genealogy centre, it will give you a list of the parishes. However, if for any reason she was christened in Carlow or Dublin City, these are not listed on the site yet.
Im from Dun Laoghaire, so Im familiar with Bray and there is a Church known as St pauls in Little Bray, and then the big church of the Holy Redeemer on main street.
These are both RC. Any others listed will have the CI after them, and there is a large CI church on the road from Shankill going into Little Bray.
Goingt on my own experience, Ive discovered that everyone was born, but no-one seems to have been married (not yet anyway

)