Obviously there are regulations and licensing regarding B & B accommodation.
Start here:
How to open a bed and breakfast in Ireland
www.gov.ie
From experience over the last 20 odd years in all parts of Ireland, nearly all today have
en suite bathrooms (usually showers only) in every room.
The going rate for B&B in provincial Ireland is ~ €60 a night with a higher tab for Dublin.
At busy periods you would therefore get more from B&B
provided you get close to full occupancy.
But full occupancy is hard to achieve except for periods of local events or well-appointed B&Bs close to say a major event centre like the Gleneagle in Killarney.
But be aware that "breakfast" today is a high expectation and high selection offering. In many places it's like what you'd be offered in a 4 start hotel - a range of fruits and juices to select from, good range of cereals, milk (cow and soya) and then a choice of rural, "full Irish" or continental main courses with a choice of teas and coffees. There is usually a range of breads on offer in both brown and white plus the mandatory toast.
What I'm saying is that while B&B can be high revenue, it is also a serious commitment in terms of provisions and service - the latter inevitably involving talking to customers and providing them with information on all sorts of things.
No longer is it enough to slap a couple of rashers and a fried egg before them and walk back to the kitchen without a word.
It's a social and relational commitment as much as an enterprise, be under no illusions on this.