Does anyone know where I need to start in getting insurance for my small business? Also, would a disclaimer form not dissolve me of responsibility in case of an accident in this field (facepainting) considering that the child would not have access to this event without parental consent??

Yes I would use a disclaimer, no it does not absolve you of responsibility in case of negligence.

Talk you're your insurance agent, then can advise on where to get the insurance you need. You may even be able to get it as a rider on your home insurance.