Oh Great Search Master, neither one of those is it. Maybe Bruce can find a slow day when the patients and the fish aren't biting and do a nice archive thread, but (as Bruce reminded me) given all the unknowns and variables involved it is useful as a "roughly how much feed will I need" tool. If the exact number and size of stocked fish to be fed is known, it would give much more precise data.
"Feed what the fish will eat in 10-15 minutes" always works.
So, Brown Lab, for #2, "Feed what the fish will eat in 10-15 minutes." With 70 acres and multiple feeders, you're either going to be feeding per a budget OR buying feed multiple times per season. How does this sound: Buy the smallest amount of feed that let's you get a price break (if available, or just get 500 lbs.) and set each feeder for a small amount (5 lbs?) per day. Observe what the fish eat and adjust accordingly.
BTW, you can make me watch Will Ferrel, but don't throw me into that briar patch.