My advice is to set clear expectations in the beginning. It is hard to take things back or change when they are already in place. I took some advice from the Singaporemaid blog and made a list of house rules for when we went out of town for three weeks (although certainly not the kind of rules singaporemaid had). My rules were things like "No guests" and "keep the doors locked." I was worried she might bring her friends over, who I hadn't even met, or that things wouldn't get done while I was away, like feeding the cats or watering the plants. I got a safe (husband made the valid point of if there is no temptation then nobody has to be disappointed in the end). We trust her, but we don't want to be taken advantage of either.
The cooking has been a trial. She wants to learn more, and I have sent her to classes. I cook with her five days a week. It is a lot more hand holding than I expected, and things I took for granted, like kitchen hygiene and not leaving chicken out on the counter all day were clear surprises to her. Tonight I had to ask her to wash her hands after handling raw chicken. She had opened up the cabinet and was touching our glassware with raw chicken hands. So, while so far it has been wonderful and life changing, the experience they bring to the table may be far different from your own. Expect some growing pains.
Things I was very clear about in the beginning, like always change the sheets on Mondays, change the kitchen towels daily, make the beds daily, do the dishes, etc., are always done. If I was fuzzy, the response is fuzzy, like how often to clean the showers. We give her Sundays off, home at 10, same for public holidays. Sometimes she stays out later for special occasions, like New Years Eve she was out until 2 to see the fireworks. I do try to get her out of the house at least once a day to pick up groceries or run a simple errand, just to get fresh air. I don't think I would like to be cooped up all day. She is good with the shopping but the list has to be clear.