Hi, I'm a quality in-home provider for over 21 years. I was licensed for about 11 of those years so am very familiar with the regulations. It is LEGAL to operate a family child care home here in Ohio without a license, however you still have to follow the STATE child care laws which states you may not have more than 6 children in care at one time which includes your own children under the age of 6. No more than 3 of these may be under the age of 2. I'm constantly amazed when I interview with families the number of providers who care for way too many kids, not just because I know it's illegal but because I KNOW absolutely that with that many children at one time, NO ONE is getting enough attention. It's impossible. Now she may just be a 'babysitter' (as you call her) who provides only the basics and therefore may have a bit more 'time' to tend to the kids, but I'm a Child Care Provider and plan scheduled activities and nutritious meals, etc. As well as forms for the parents of my infants that outline specifically what their baby is eating, how much, and when.
One of my first thoughts after reading your letter is that some of what you are going by is 2nd hand information which may or may not be true.
I would NEVER EVER go outside to mow while caring for kids even if they were all sleeping. That's crazy.
I can also tell you that she IS probably propping your daughter's bottles.
This is a no-brainer. You have to find new care. Please look for a Provider and not a babysitter. He/she does not have to be license but should provide quality care. And yes I know it's extremely difficult to find that. But IMO you are putting your child at risk if you do not.
Also please drop in unannounced at an odd hour, I have the feeling you are not going to like what you find.