Some of these pond consultants/contractors can do topographical kind of maps of your pond basin. That's definitely helpful, if not essential, to know. You could achieve the same thing with a boat, string and a weight and a few hours of time.
You could have an electroshock survey done either now or sometime in the future. Much of what could be learned from such a survey could also be learned from hours and hours of fishing and observation. Both options put together give the best 'view' of the fish life in your pond.
Water quality tests could also be done.
