(O’) Driscolls in Fossa, Aghadoe 1775-1825

Hello! I am wondering if perhaps anyone can give me some guidance as to how to proceed in my search for my Fossa ancestors. I appreciate any advice on this. 

My ancestors are Stephen Driscoll and his wife Catherine Rahilly. One of their daughters, named Mary or Margaret married John Ford from County Cork (exact location unsure.) I got the names from my third great grandfathers (Jeremiah Ford) death certificate, which  I am leaning toward being correct as his oldest daughter was the informant.
 

I have been on IrishGenealogy.IE and found what I believe to be all of Stephen Driscoll and Catherine Rahilly's children. On the baptismal records I also found names of possible relatives, as sponsors, or witnesses to marriages for each other, etc. Their children were all born between about 1800 and 1825. 

I have not been able to get back any farther on either Catherine's parents, or Stephens. I have also been unable to find any kind of marriage documentation in either County Kerry or Cork. The family was Roman Catholic, so what I have been able to ascertain has been from church records.

How can I learn more about the areas of Fossa and Cools?  How can I learn more about where the families may have come from before coming there? I have found Stephen in the tithe applotment books. I would love to pin down birth and death dates or at least a good guesstimate. Also, there is a huge 7 year gap between all the children of Stephen and Catherine and the last two of their kids. Did something happen in Fossa during the late 18-teens to early 1820's? I just have so many questions. Is Fossa still a place, and if so, what is it like? Or what would it have been like back then?

Thank you so very much for your help, it is truly appreciated! Jacki Wilson in Ohio, USA