I also find having a live in helper a very positive experience. I had a part-time helper for a year-and-a-half, but when we started planning a family, I wanted to hire a full-time live-in helper.
You should be very careful in choosing your helper. Mine is the niece of my former part-time helper, who we loved and trusted. We hired her from the Philippines directly (she had never been to Hong Kong before) and, therefore, it was important for her to start with us before the baby is born so that she could get to know us, our family and Hong Kong!
Although your helper is a 'stranger' at first, you will get to know her very quickly (if you take the time)! If she is a good person and genuinely interested in her job, she will also get to know your family and your personal preferences. Ask many questions when you interview - try to get to know the person rather than focusing on the skills they have. Someone who takes pride in themselves and their job will be a great helper.
It definitely helps for her to have her own room - It allows her to truly enjoy her private time, and to have her own space to go to when she needs to rest or talk to her friends and family.
My baby is due in November, but we have a small dog, so our helper gets up around 7am and feeds the dog, tidys up the living room/kitchen while we get ready. After we leave she tidys up our room, starts laundry or does some more 'deep cleaning' like windows, cleaning the refrigerator, etc.
I do not work, but I do spend my mornings out of the house most days, at classes or meeting friends. If I am home, she works around me. I do feel lazy at times, but I know that I could not do as good and thorough of a job as she does - she is truly a professional - ironing sheets to a crisp, polishing silverware, dusting curtains (stuff I would almost NEVER do)! I did make a basic chore list for her (outlining daily, weekly and monthly chores) - but she always comes up with stuff I never thought of - like ironing sheets, or alphabetizing movies!
She takes breaks whenever she wants, when the laundry is drying, or if the chores are light - she has a TV/DVD player in her room and we paid for half of a very basic computer - which she can use our wireless connection to chat with her friends or email. We also set her up with a nice bunk-bed with desk and armoire below - and I never enter her room without asking, it is her private space.
Her job is normally finished after dinner (8pm or so) and she retires to her room. If we have a dinner party, and she stays up late to help, we tell her to take the next morning off, which means she won't start until noon or so. The only meal she cooks or assists with is dinner, and I usually give her advance notice if we will not be eating at home so she can arrange her dinner.
She eats what we eat, but does not sit down to eat with us. We do have chats about her family, her church, her studies while we are cooking together, or if we run errands together.
If you've ever hosted a work-study student, or been one - the situation is similar to that. You are exchanging room, board and a stipend, for work. You should respect your 'boarder', or helper's privacy, and provide them with a comfortable place to call their own. They, in turn, should respect your family's privacy and the work schedule or tasks that you have set.
Hope that helps!