How do I prepare the soil to make bricks?

My ground is across the highway from Riverdale, KS and though nearby fields grow wheat, soybeans and etc. I have difficulty growing a garden in it. This dirt is so thick that when I drilled post holes for the cesspool (other people call it a lagoon) I had to drill a little at a time and soak the holes with water so the drill could get the dirt to come up out of the holes. The dirt came up as small balls of clay.

1. How do I test the dirt for clay-brick quality?

2. How do I get all the grass roots out of it so I can make consistent great quality bricks?

3. Do the bricks need to be fired so they will be excellent house building material?