Obviously there are regulations and licensing regarding B & B accommodation.
Start here:
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.