You're not wrong about the split in Irish football. After that, I'm afraid, you're all over the place.
There would have been some shameful anti-Protestant attacks (often - but certainly not always - the settling of personal scores) in the immediate aftermath of independence but it really didn't last very long in the Republic. Mostly because the small Protestant population (6% or so) posed no threat to anybody.
Trinity College Dublin (back, in the day, an exclusively Protestant institution was guaranteed representation in the Seanad (equivalent to the House of Lords) in the 1930s and before Douglas Hyde - the first President elected in independent Ireland - was a Protestant.
There was no gerrymandering of votes, no active discrimination in housing and employment like there was against Catholics in Northern Ireland. It's simply not accurate to equate the two.
All Irish cities still have active Protestant Cathedrals that are still in regular use. Small towns like Killaloe and Bandon in Clare and Cok still are and always have been predominantly Protestant.
Arthur and the rest of the Guinness family were famously Protestant Dubliners (and Unionists too). Their business was always rather successful than say, the Catholic-owned (I think) Murphys. I have no idea if they have converted since. Like most people in Ireland (as opposed to Norn Iron), I simply don't care.
