Can atv be uses in the Park ?

Yes I think so. The last time I was there I saw like 2. But you can call to ask them they'll explain better

I haven't seen atv's at the park, not sure.

I am sorry, I don't know. If it is allowed in state parks than probably yes, you may only be allowed on the main road. But I do not know for sure, I have not seen them there.