If in a bath and all together as posted photo ?! NO Splash. There is already too much going on with counter top and flooring . The counter has a riser and the wall needs no more than that for protection.

off white tile. As the floor and counter are busy, I'd keep the tile simple.

I am not convinced all of those go together, but if you do not have a 4" backsplash already, I would do something plain and simple.

You have a backsplash. If picture is representing what your actually working with