1) if you are going to renew the contract with your helper, ask her to give the regisnation dated Aug 2013 in advance so that she won't claim the long service.
2) my helper was similar to the one you are considering: 6am-1am + shared room with 2 small kids and grandma + holiday 11am-7pm. As she was referred by a friend, we hired her after she gave the resignation to previous employer. She is Ok overall until now (works for us for 1 1/2 years). It's hard to say it's trustable or not. It depends on luck.