Back to the original poster. Setting up a BnB is relatively straightforward. You don't have to be registered with Failte ireland (and its not worth the hassle going down that road).
Its perfectly fine not to offer breakfast. Increasingly room only accommodations are popping up, particularly with the advent of Airbnb and with many providers cancelling breakfast over covid and choosing not to reintroduce it. As regards health and safety you dont necessarily need Haccp, fire alarm systems etc etc. There are bnbs throughout the country that have been going for generations that never had an inspection from anyone. However you do open yourself up to liability issues if there is a problem down the road. All that is really needed to open a b and b is to stick a sign on your door and thats you up and running. There's no one really regulating anything. You can't call it a guesthouse without registering with failte ireland but "xxx accommodation" or i think "xxx b and b" is fine.
Forget about the €100 rate. Ukrainians are being housed for a variety of different rates depending on how they're placed (community groups / council etc) but I'm aware of hotels getting less than that. Many hotels will be withdrawing their rooms for the summer so the rate may have to rise but that isn't the going rate at the minute. And without proper facilities you aren't going to be getting the top rate. Councils rates are different throughout the country but they'll depend on the going rate in the area.
Insurance may be affected - typically you'd pay about 2k for a small bnb. Tax will depend how you decide to set it up.
Hassle: mountains more than he envisages. If he's thinking of just leaving everyone at it he still needs to meet people to give keys. If he's living on site this Will mean people arriving after check in closes, bringing people back for a party, damaging property, noise complaints. For a bottom of the market type property therell be regular visits from the gardai for various reasons. Cleaning, maintenance, responding to guest requests, dealing with overbooking, dealing with troublesome guests. If he's not going to be hands on or have someone in who can run it for him it will be a dump in no time and that brings its own problems (the only people who'llstay once the review score drops will have various issues. The council won't place anyone in properties that cant maintain a basic standard). If he's going to do it, he would be making a rod for his own back to do it any way other than somewhat well.
It is however fairly profitable at the moment. And would almost certainly generate a better return than renting.
As regards the male / female debate, I have 4 full time employees - breakfast reviews are better generally when the 2 male ams are on but overall there has been little notable difference. And I've always found it easier to find males for this kind of role (for the size id expect he'd want any hire to be able to do a lot of different tasks, not just cook for 2 hours). Thats an opinion based on many thousands of reviews and direct feedback which I'm reluctant to give because the whole "debate" is so laughably ridiculous in the first place.