Meaning of reusing water in wudhu

Q: I’ve heard from someone that it is impermissible to reuse water for wudhu, however if someone lets the water from the tap run over his arm such that only one side of the arm is being directly hit with the water and the other side is getting wet by the water flowing over the arm, then will this be a valid wudhu?

Placing a plaque with a short dua instead of the donor's name on a well

Q: There is great rewards in making sadqah in the form of wells. I wanted to know if on the well it is permissible to have a dua instead of the donors name. There are wells I've contributed towards, but charities insist on a donor's name. My intention was to make Allah pleased so I requested short duas on the plaques instead. So the benefactor remembers blessings. Is this permissible?