Do I use the toe slab as my basement slab (I would have both top and bottom rebars)?

Typically, your floor slab would be poured on top of your toe slab. Otherwise, you have a problem of the shear at the end of the toe. Unless you really thicken the slab and increase the reinforcement you will get a large crack at the end of the toe. Most designers and engineers avoid this by placing the slab on top of the toe.