What is the ruling on following a specific madhhab, such as the Shafi'i madhhab? Is it obligatory to adhere to everything mentioned therein? Is it permissible to take directly from the Sunnah without being bound by a specific madhhab, and what are the controls for that? What are the books that one can start with to follow the Qur'an and Sunnah directly?

A Muslim must obey Allah and His Messenger, and the scholars who act upon the Qur'an and Sunnah (definition). Following a specific madhhab (definition) (school of thought) is permissible, not obligatory. The correct view is that it is not necessary to adhere to a single madhhab, and there is no objection to following more than one. What is commanded to be followed is the Sunnah of the Messenger of Allah, peace and blessings be upon him. This does not mean switching between madhahib for the purpose of seeking concessions, but rather adopting the opinion that has the strongest evidence.