how to list currently active gesture recognizers?

Use the UIView's gestureRecognizers property:

for (UIGestureRecognizer *recognizer in self.gestureRecognizers)
{
    //Do something with recognizer
}

More reading: UIView

You could have a bool for your class and set it to TRUE when the recognizers has permission to do stuff. When you want to disable them you can set the bool to FALSE in your recognizer methods. You just have to test if the bool is true or false before doing the stuff that you need to.