Is it permissible for a Muslim to adopt a legal ruling from one of the schools of thought when they differ on a certain issue, and is he obliged to adopt the preponderant view of the majority of scholars, and can he adopt different rulings from multiple schools of thought on various issues?

Those capable of independent reasoning (Ahl al-Nazar) must follow the preponderant opinion. As for the one who adheres to a specific school of thought (muqallid), it is permissible for them to adopt rulings from different schools, as long as their intention is not to seek out concessions (rukhsas) and anomalous opinions (shadhdh opinions). The consensus of the Companions on the permissibility of seeking rulings from any of their scholars indicates the permissibility of this. However, pursuing concessions out of mere desire is unanimously prohibited.