There are tons of threads on this website about various agencies etc...so do a search. How long to hire one? It depends if you are bringing one directly in from the Philippines or one that is already here looking for new employment once their current contract is finished. Best advice is to ask your friends about agencies. It terms of looking for a helper there are number of ways and not one is better than another - it's kind of all luck, but here they are:
-ask your friends who know of any and to fwd emails on to you esp ones with children in schools
-ask your friends helpers who you like, if they know of anyone looking
-through an agency
- look on websites like asiaxpat.com
- if you know of any families returning to their native country, ask them about their helper
Once you've found a helper you like, you interview them and ask them all the questions you want. Some do a trial morning (cook something, iron, play with my child etc...) so they can be observed. Of course, ask for references and why they are looking for a new job. If you like a person, be ready to offer a contract right there and then b/c good helpers go fast. Chances are by the time you decided you want to hire, they've already found a new job. Their day is totally up to you and your needs. Our helper is up at 6am and eats her breakfast for a half hour. She finishes at 8:30pm with a 2+ nap/rest time in middle when our son naps. Our helper gets all sundays off and statutory holidays off unless otherwise agreed upon.
Hope this helps!