Is it permissible to pray the single rak'ah of Witr after 'Isha' and postpone the two rak'ahs of Shafa' until Fajr after praying some rak'ahs, and does supplication affect the course of destiny?

It is permissible to pray Witr with a single isolated rak'ah, although some scholars, such as the Hanafis and Malikis, consider it disliked. The minimum for Witr is one rak'ah, and the maximum is eleven rak'ahs, as held by the Hanbalis and Shafi'is. If someone prays Witr before sleeping and then wakes up, they may pray as many voluntary prayers as they wish, and they do not need to repeat Witr, because there cannot be two Witr prayers in one night.