What is the ruling on wearing wool imported from India, given ignorance of its source? Is it obligatory to investigate its source? And what is the ruling on using angora and other types of wool?

It is permissible to wear wool imported from non-Muslim countries, whether the wool was shorn from a living or dead animal, because the wool and hair of a dead animal are pure according to the majority of scholars. This is the madhhab of the Hanafis, Malikis, and Hanbalis, and it is one view among the Shafi'is. Sheikh al-Islam Ibn Taymiyyah held that hair and wool from all animals are pure, basing his argument on the principle that they are originally pure, the absence of any proof of impurity, and that the prohibited dead animal is that which possessed sensation and voluntary movement, whereas hair grows and is nourished like a plant, not an animal. The conclusion is that it is permissible to wear wool imported from infidel countries without needing to inquire about its source or the animal's life, and even if it is assumed that hair or wool from an impure animal is mixed in, its use is permissible and it is pure according to the preponderant opinion.