YES, the wildlife along the rivers IS amazing. DON'T wander the banks with your camera. Go to lookout points specially made for this purpose. Many of the rivers have crocs in them. They will attack.
People do die here from crocs.
YES, you can wander trails in the National Parks. But these are not your park down the road. They are parks in name only. They are wild jungle. Many have guides you can hire to accompany you down the trails.