Searching for Treacy and Doughan ancestors

My cousin and I will be visiting Offaly in June to research more information about our Treacy and Doughan ancestors:

1.  Denis Treacy (2x great grandfather), he was likely born in the 1830s; I don't know the names of his parents or siblings.  He was a farmer in Clonlisk, and he married Julia Doughan on 17 Jul 1862 in Shinrone Parish (Diocese of Killaloe) - the witnesses were Thomas Madden and Bridget Flannery.

2.  Julia Doughan (2x great grandmother), she was likely born about 1839 as she was listed as 49 years old in April 1888 when she emigrated to New York with her children.  I don't know the names of her parents or siblings. 

3.  Denis and Julia had 8 children: Timothy (28 Jun 1863), Michael (8 Mar 1865), Edward (31 Jul 1867), Margaret (22 Aug 1869), Mary Anne (1 Sep 1871), Catherine (23 Jul 1873), Martin (2 Dec 1875) and Denis John (4 Mar 1878). 

4.  The Shinrone Parish Marriage Register recorded the 17 Jul 1862 marriage of Denis Treacy and "Judy Dohan."  Also, the baptismal register for the first 6 children record the parents as Denis Treacy and "Judy Dohan."  The Civil Registration Birth record for the youngest child records the parents as Denis Treacy and "Julia Doughan Treacy."  We would like to confirm that the correct first name is actually Julia and not Judy.

5.  The Valuation Office Books for Frankfort in October 1850 and Griffith's Valuation for 1851 list (i) Denis Treacy on property #33c and #34; (ii) Timothy Tracey on property #9a; (iii) Edward Tracey on property #9b; and (iv) Patrick Tracey on property #28a&b.  How can we determine which of these persons might be related to us?

6.  The Valuation Office Books for Frankfort in October 1850 and Griffith's Valuation for 1851 list Michael Doughan on property #33b.  This would seem to be in close proximity to property #33c and 34 which were occupied by a Denis Treacy - perhaps that is how our Denis Treacy and Julia Doughan met?

7.  The Valuation Office Books for Glass House for August 1850 and Griffith's Valuation for 1851 list Michael Doughan on property #11b.  How can we determine which of the Treacy / Doughan families are our direct ancestors?

8.  The Valuation Office Books for Clonlisk for 1850 and Griffith's Valuation for 1851 list Cornelius Tracey on property #9a.  I think this is the least likely ancestor as I have discovered no one else in the family tree named Cornelius.

9.  Possible siblings/cousins for Denis Treacy (based on names of his childrens' baptismal sponsors) could be Edward Treacy, Mary Anne Treacy, Margaret Treacy and Patrick Treacy.

10.  Possible siblings/cousins for Julia Doughan (based on names of herchildrens' baptismal sponsors) could be Julia Dohan and Martin Dohan.  Also, perhaps Bridget Flannery and Eliza Quinlan were Julia's older sisters who had married??

11.  A relative told me that Denis Treacy died about 1-2 years before his wife, Julia, and their children emigrated to New York in April 1888 (although their son, Michael, emigrated on a different date).  I have not found any Civil Registration Death record that corresponds with that time frame.  Are there other records we could search to determine the date of Denis' death and where he is buried?  What Catholic cemetery would someone from Clonlisk have been buried in in the mid- to late-1880s?

I would greatly appreciate any guidance that you might be able to provide!

Sincerely,

Margaret Riley