Does touching the face with the hand while renewing the water for wiping the head during ablution necessitate re-renewing the water? And is it sufficient to wipe the remaining part of the head by renewing the water and sufficing with repeating the wipe, knowing that repeating the wipe is a Sunnah? And is the end of the head that must be wiped at the nape of the neck, or does it include the hair growing on the neck?

The Sunnah regarding wiping the head is to do it only once, by bringing the hands forward and then back. This is sufficient by agreement. The majority of scholars do not consider it desirable to repeat the wiping, contrary to Shafi'i and Ahmad in one narration. The jurists have mentioned that the manner of wiping is to place the index fingers at the front of the head and the thumbs on the temples, then move them to the nape of the neck and bring them back to the front. The boundary of the head for wiping extends from the usual hairline to the nape of the neck. Wiping the hair that hangs down onto the neck is not obligatory according to the majority of scholars, whereas the Malikis consider it obligatory. Therefore, wiping once while covering the entire head is the Sunnah, and if you are certain that you missed a part, then wipe what you missed.