Sunnats and aadaab of wudhu

Q: Some books mention that one should recite Surah Qadr after wudhu. Example Talimul haq, practical salah by Talimi Board.

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?

Q: When making wudhu using a mudd, what is the preferred sunnah method, does one throw the water in the palms and then use it for each limb, or can one merely submerge the hand in the utensil and use it that way, after washing the hands first?

Q: Is it sunnah to use new water each time when washing each limb (when making wudhu)? Or can one take 1 scoop of new water for each limb (in the instance when using a mudd) and rub the limb 3 times? Which way is sunnah?

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?

Q: Is it sunnah to renew the wudhu before sleeping or will the wudhu made previously suffice?

Q: My face is oily. When I am performing wudhu, some of the oil of my face gets onto my hands. Do I have to rub my hands with water to ensure that water gets underneath the oil and reach my skin?

Do I have to rub any part of my body if the oil of my face gets onto them (for example my forearms, my feet)?

In that same logic, if oil from a part of my face (the left part for example) get onto or mixes with the oil of another part of my face (the right part for example) do I have to rub that area with water (the right part of my face)? 

Q: If a person performs wudhu by spraying water using a spray bottle and wiping the required parts without water falling on the ground, will the wudhu be valid? Is there a requirement that water should fall on the ground while washing in wudhu?

Q: How many litres of water would Nabi (sallallahu alaihi wasallam) use for wudhu and for ghusl?

Q: If the nail gets long and were not cut in a week, will the wudu and namaz still be valid?