That sounds like a wonderful career change!

Yea, there are bacteria in soil. and I was a bit worried about that. but Diane Walstad routinely uses soil as a substrate in her natural planted tanks with no problems. I was really impressed by her book, the ecology of the planted tank. That's why I'm shooting for an ecosystem type thing rather than minimizing debris in the tank. Soil may actually help with removing nitrAtes to some degree.
It's like the antithesis to bare bottom tanks tho. The whole goal there is to minimize the debris and bacteria that consume those debris. Bare bottom should work well to reduce the ammonia load of the tank and the bacterial count in the tank as long as you have good mechanical and biological filtration.