Is the tawarruk sitting posture a Sunnah for the ma'mum (follower in prayer), or only for the imam (prayer leader) and the one praying alone, especially considering that a ma'mum who performs it might inconvenience those praying next to him?

The jurists are of the opinion that tawarruk (a specific sitting posture) in the final tashahhud (definition) is a sunnah (definition). This is the view of Malik and Al-Shafi'i. Ibn Qudamah elaborates that tawarruk occurs in prayers that have two tashahhuds, specifically in the latter of them. As for Al-Shafi'i, he holds that it is sunnah in every tashahhud from which one performs the taslim (definition), even if it is not the second one. Tawarruk is a sunnah for every worshipper, whether he is an Imam, praying alone, or a follower, due to the comprehensive nature of the Prophet's (peace be upon him) statement: "Pray as you have seen me pray." The followers should apply the sunnah of tawarruk while avoiding causing discomfort to their neighbor, and those who are ignorant of this sunnah should be advised by teaching it to them.