Greg, you won't really "save" any money with a compact tractor. As for the trees, "save" money by pushing them down with a dozer, then cutting logs. It will take a LOT more time ($$$) to dig out the stumps of cut trees.

Get some elevations to know exactly where, and how high any dam will need to be to accomplish your goal. Then make as accurate drawing as possible of the new pond's shape, and draw in any structure features wanted to give the pond builder. It cost's a lot of time and money doing things as they come to mind, versus it being all built at the time.