The price level is probably best determined by comparing similar listings through the website. In my opinion, after location, the price is mainly determined by the number of rooms and the general appearance. Other amenities are mostly a plus. For example, in the summer, people do enjoy air conditioning and praise it in reviews, but they don’t necessarily include it as a requirement in their search or pay extra for it.
The price varies on a daily basis according to demand. During festivals and other major events, the price can easily double. It’s worth researching these and setting higher asking prices in the calendar.
I would put in one double bed and the rest as single beds. In one room, use single beds that can easily be joined into a double bed if needed. Various work crews prefer to sleep in separate beds even if they share a room. I recommend 90 cm beds according to Swedish dimensions; it provides a nice bit of extra space compared to the Finnish 80 cm.
The price on Airbnb is structured as nightly rate + extra guests per night + cleaning fee per stay. Cleaning is very expensive in Finland; cleaning a detached house like that can easily cost €150 every time. Therefore, the minimum stay should be at least two nights. A two-night minimum also reduces all the other constant “rumba” (hassle).
As for what kind of people rent these, you asked. It depends entirely on why people travel to your area. It could be business travelers, gig workers, trade fair groups, sports clubs or teams, tourists, or people evacuated from their own homes due to, for example, water damage.