Firstly i am sorry to use informal language below.

-For making my najis area(anus) pak after pooping, I use shower to wash it. The water comes in force and I put the direction of water on the najis area to make it pak. Then, while washing, due to the great force of water, the water touches the najis area of anus and then the water splashes all around due to the great force. My question is that:-
1) The water that splashes all around is also najis?
2) The water then splashes all around and goes to skin and reflects back, so the areas which get touched to that water also become najis?
3) If the skin which is touched by the water become najis, then will it have ability to transfer the najast to another thing also?
4) When the poop falls in the sink of commode, the water in the skin spashes back upwards and hits the hips. So hips also become najis?
i want add one more thing ..which is that the water I am using comes from a water tank through a shower in my toilet.

If the water container is 374 litre or more then:
if water touches on faeces itself then its splashes is najis. If That splashs goes anywhere that will be najis as well