Oh goodness, no, I wouldn't expect any fast food or anything like that at all. I've always thoroughly enjoyed Irish culture and music, and one of my silly dreams is to be able sit in on a music session in a pub. I play a lot of irish flute and whistle, but I don't know how I well I would be recieved. I've been thinking about staying towards Cork, and staying towards the south.
check out this site.........
http://www.touringireland.net/horse_riding.htm
As for going in a pub and joining in, you would be most welcome, the more the merrier (literally) is the motto.
A fish and Chip shop is the most you might find in the way of fast food. Pubs almost always serve bar food and mostly it's great. Homecooked and expect to wait! Some pubs (INNS) have accomodation too.
Expect most everything to be closed on Sundays and it used to Wednesday afternoons too! If you stay in a cottage, most of the time the electric is on a meter and you will need to find out the coinage required beforehand as those meters eat coins like kids eat sweeties (candy).
However, if I were to reccomend anything to someone, it would be that to experience true Ireland, stay in a cottage and find your own way about the place. : )