Spawn Patterns

[WIUbassin]

Last year I caught my biggest fish(largemouth) to date, 6lbs 10ounces. I know that may not sound that big, but for upper Illinois thats pretty decent I think. I reeled here out of a 4acre interstate(I-57) pond. It was on april 13th last year and spawn had just began to kick. I am relativly sure she was sitting on her bed. Anyways, I have fished this pond for 5 years and the biggest largemouth I had pulled out of it was around 2 1/2lbs so naturally I didn't bother to bring a camera(I still curse my decision to this day).
With that in mind I have two questions.
1. Do females return to the same location every year to spawn?
2. If I never see this bass again how would you guys go about catching the biggest bass in the pond? The ponds eco-system is really wacky. It has an extreme overpopulation of 6-8inch bass and apparently only 1(6lb 10ounce) lunker. The pond looks just like a big (fish)bowl with a couple of points where people have dumped huge slabs of torn out concrete. Other than that just cattails. With all that being said, What techniques would you try to have the best chance of pulling the trophy fish?