Your research shows lots of good work. Now please don't get cross with me for noticing, on a quick scan only, that it appears that Margaret (Denn) McQuaid --- was buried before she died? Maybe a typo, or a different person.
Thought "MCQUAID, William A, age 33 [in 1871] - ONTARIO, Northumberland East, Percy" - might have been father or uncle of the person you are researching, thus supplying earlier location clues. After a long wait, once I obtained several pages of photocopies of actual census pages from Canada, using the URL: http://www.archives.ca/02/02010802_e.html
Database for Illinois Marriages: http://www.sos.state.il.us/depts/archives/marriage.html
This IRAD site is "down" right now. There may have been additional McQuaid or other family marriages in Illinois. Your Wm McQuaid was a widower at age 40.
IRAD used to have an online database of early births in Illinois. It seems that now you must write to them for birth info. Very inexpensive, although very slow turnaround.
California databases online, for Deaths and Births are listed below.
This fountain of information about web sites took me several years to collect. Hope they help you, as well as anyone who notices this reply.