Lsmth,
I would definitely consider renting a big, fat excavator (if one is available in your area). It will do a months worth of tractor work in about twelve hours. You can use your Kubota FEL to move the spoil around, and do some detailing work once the main digging is done. Even that will be a lot of work for a relatively small machine. Compact tractors are not designed for what you are proposing.....3+ acres is a whole lot of earth to dig and move. You can rent a excavator for a couple hundred bucks a day plus transport. They're not that hard to use either. -I just dug my foundation with one and got within one inch of where the septic was supposed to drain.....had never used one before. If you are going to rent one....get a big one. They're not that much more money than the smaller ones and they're no harder to operate, providing you have a clear area and are not bound by power lines or big trees that might damage the machine.
Don't get me wrong, excavtor work is a skill / art. It will take some time to get proficient. Although, even an unskilled operator can do way more work in a couple of swipes than a compact tractor can. -Finish it up with your machine and spare it the hours and abuse.
Dig your pond deep where the stream enters, or better yet, build-in a "silt pond". You'll be amazed how fast it will fill in with sediment. Our pond's silt pond should be cleaned out annually, but we do it about every three-four years.
Go nuts, and rent a big one /forums/images/graemlins/smile.gif
-Jim