Scratch that. I've now added a fourth worksheet.
It's entitled "Required Water Calculations." Not so surprisingly, it calculates the amount of water that you need for your all grain brewing based on a few parameters. In particular, those are: batch size, pounds of grain mashed, evaporation rate, boil time, and water lost to dead space.
I've also included cells that calculate approximate amounts of yield from the first runnings, as well as how much spare water you'll require to achieve the proper pre-boil volume in your kettle.