From your query it is hard to discern whether you are the host, the performer, or possibly both.

Two 45 minute sets plus a 15 minute intermission is the norm for house concerts. The break usually stretches to 20 minutes or more if you have only one bathroom and you are also selling CDs.

As far as the suggested donation, the performer usually gets 100% of the take if you are not locked into a guarantee. Most house concerts do not work with a guarantee but you can not always count on attracting a tier 1 performer.

At the house concerts that I host (The Borderline in New City, NY) we guarantee at least $300 if it is a single performer and $600 if it is a group. Anything over that gets split 60% for the performer and 40% for The Borderline (which by the way is a non-profit all volunteer run organization). By posting guarantees you will attract more well known performers and therefore have a better chance at attracting a large audience.

In order to minimize expenses I would also suggest that you do a pot luck lunch or dinner depending on whether you are doing an afternoon or an evening show.

As far as young children are concerned, be up front with the people and tell them in no uncertain terms that small children who can not sit still and behave themselves are not welcome because they will disturb everyone else who is trying to enjoy the music. Our age limit is no one under 12 and we are strict about it.