Sunnats and aadaab of wudhu

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?

Making masah on medical socks

Q: A person has a medical condition where water fills in his legs. He has to wear a stocking/sock that is very tight. This sock helps mitigate the condition. It is very difficult to take off and put on the sock.

In this situation, will it be permissible to make masah on these socks in wudhu?

Washing limbs more than three times during wudhu and water reaching the skin under the beard

Q: During wuzu, it is sunnat to wash the limbs of our body 3 times be it the face, hands or legs.

1. What if we feel that on 3 times we haven't fully wet the particular limb, can we then wash a particular limb more than 3 times? Will this invalidate the wudu or that just means we will leave the sunnat but wudu will be done?

2. As for cleaning the face during wuzu, is it necessary that water reaches in the gaps and the skin below the beard/moustache?