If I have both oral and genital herpes and my 4 year old son used my tooth brush by accident while I was using it he grab it does he have it now?

Unlikely . Most people with a history of oral herpes have relatively few outbreaks, and herpes virus is rarely active in those individuals. You'll have to wait and see if he develops oral herpes lesions. Genital herpes is only spread by local contact, so that's not a concern in this case. See your doctor to discuss treatment if you are having outbreaks of either kind for intermittent or suppressive therapy.
It depends... If you have the active phase of the disease, break out in your mouth or lip, then it is possible. But if he has strong immune response, he may be protected. It is better to keep your tooth brush away from your family especially in the active phase of the disease, change tooth brush immediately after. Also ask your physician or dentist if Valtrex (valacyclovir) can help you.