You don't say where you live but in Ontario for instance you can have 5 daycare children only so even doing just before and after school care you can only have 5. Therefore you don't really make any money because they tend to eat a lot more so what you actually make for their care goes towards food and craft supplies if you provide them for after school. For sure you will not make anything in terms of income that will come close to equalling what you earn now.

You are not allowed to overlap children either so even if some go to school in the morning you could only take on younger children between school hours and then not take the school age group for full days on PD, school breaks etc which many parents won't like.

Many who do just before and after school have some sort of personal job that they do while the children are in school and often one they do from home just in case school is closed and kids are home all day.

For sure you can charge a premium for French only care in many cities because it is harder to find. As for the buses you will need to find out what buses come to your area now and where the bus stops are. Then you will need to advertise only for children that go to those schools. This info will be available through the school board sites showing what your neighbourhood schools are.