Vasectomy

Q: Can a man have a vasectomy? 

He and his wife have both agreed this is the best way forward because they do not want anymore kids and she does not want to go on any medication or injection. Is a vasectomy allowed in Islam?

Drinking the leftover water of wudhu whilst standing

Q: What is the ruling of drinking the leftover water of wudhu (fadl wudhu) whilst standing? 

In Dars Tirmizi (vol. 1, pg. 259) — taken from Duroos Madaniyya of Moulana Husain Ahmad Madani رحمة الله عليه — it is mentioned that Ibn Abidin (al-Shami) did not regard it as mustahabb, and that the ahadith on this issue cannot be used to establish istiḥbab. 

However, in Fatawa Mahmoodiyyah (vol. 8, pg. 123) the words of Ibn Abidin (al-Shami) in Radd al-Muhtar are quoted as proof that drinking fadl wudhu whilst standing or sitting is mustahabb. 

My questions are: 

1. According to the Hanafi madhhab, is drinking fadl wudhu mustahabb or not? 

2. What is the correct position of Ibn Abidin (al-Shami) in this matter? 

3. If it is mustahabb, is it specifically recommended to drink it while standing, or is sitting still better? 

4. How should the apparent contradiction between Duroos Madaniyya/Dars Tirmizi and Fatawa Mahmoodiyyah be reconciled?