Ghusl - Water used for cleaning najasat

Question: I make a ghusl using a "pot type thing" to pour water over me.
When cleaning najasat during a ghusl, is the water used considered najs when soap is used to clean? I cannot tell if it definitely contains traces of najasat, but it most likely does. If the used water is najs, does the bath floor and the underneath of my foot become najs? If so, does it suffice to pour water along the bath floor to clean both the bath floor and my foot?

Walaikum assalam,
 
1. Unless you are CERTAIN there is najasa on your body, then your body is free of najasa. The fact that it is "likely" or even "inevitable" that there is filth on your body is of no consequence. You can only be certain there is filth: (a) if you can see that which is (by its clear attributes) filth or, (b) you saw the filth clearly get on your body.
 
2. The sunna is to was the filth (najasa) off before you perform the wudu that is the first action in your ghusl. If you do this, then when you shower, your Questions below are of no consequence.
 
3. The water that washes away the filth (najasa) is filthy. Any water after that is pure. If pure water flows over your body and on the ground, it is considered to have washed away the filth that could have fallen on the ground, or the traces of the filthy water, unless any clear signs of filth (colour, smell, or taste) remain. The possibility of it having "splashed here or there" is not entertained. As such, it is absolutely not necessary to pour water along the bath floor, your feet, or elsewhere. Save the water for the plants.
 
Wassalam,
Faraz.