For the Murphy's I know for sure they were from CastleIsland. So I assume St Stephens Church? If that is any help at all to nail down the likely graveyard in the early to mid 1800"s?
St Stephens & St Johns Church in Church St was built in 1884 and I don't believe there is any graves on site - Don't recall seeing any anyway.
St Stephens Church in Church Lane was built in 1840 but remains there going back to about 1600s. There are some graves on site there.
The main graveyards that were used were the Kilbannivane graveyards (Maher, Pembroke, Old & St Johns) and dependant on where abouts in Castleisland they lived it could have spurred out to the Cordal, Currow or even Knocknagoshel ones. You may find it difficult to trace back graves from early to mid 1800s as they may not be in a good state due to erosion and therefore not transcribed - or like it was said previously a lot of people couldnt afford headstones and therefore just didnt have them. I know a lot of my family in Castleisland didn't.
Another good place to check is
http://www.kerryburials.com/ this gives a map of the graveyards and pictures of the graves there. Have you managed to find the death records of these people as it may help understand where they were recorded as having died.
For the O'Connors - I am still unable to nail down the exact town but working on that. All I know for sure is they lived approx 7 miles from Killarney. Patrick b 1818 d 1878 married Ellen Fenighty (Fenton) or various other spellings -also b around 1818. They were also RC
Have you managed to find the Marriage details of this couple? That would help point you on your way - am guessing not as of yet as you would know where they were from initially. There were lots of O'Connors about as im sure you will know so again may be a difficult one to trace back.
If you havent found the marriage could it be this one?
http://www.rootschat.com/links/01jeu/Firies is not far from Farranfore - about 9-10 miles out from Killarney.