I'm afraid I can't help you with Johanna although I've had a good look. One theory is that she might have been a twin and just one name was written down - just a guess but it happened in my tree. As for the marriage and parents etc:

Maurice Quill (Knockalougha) m. Julia Hickey in Duagh parish church on 2nd N.R. 1858. The witnesses to the marriage were John Quill and Cornelius Hickey. You can take from this that Julia was from Duagh parish.
After a quick search on irishgenealogy.ie, the only Julia Hickey that I can find baptised in Duagh was on 30th Sept 1838 to parents Cornelius Hickey and Margaret Riordan. This seems too good a match esp. when Cornelius name appears on the marriage record.
The children of Cornelius Hickey & Margaret Riordan are:
Denis b. 30/11/1831 - Duagh
Joanna - 10/07/1833 - Duagh
Patrick - 28/03/1836 - Duagh
Julia - 30/09/1838 - Duagh

I can't find a baptism for Maurice Quill so that could be another problem area for you

EQ