Is it permissible to eat the food of, and enter into financial transactions with, a Hanafi friend who engages in corrupt contracts in Europe, and is it permissible to condemn him?

If your friend engages in usurious contracts in Dar al-Harb (land of war) emulating his Hanafi madhhab, there is nothing upon him; because the Hanafi madhhab is recognized, despite the existence of anomalous issues that should not be adopted. The correct view is that usury is forbidden in Dar al-Harb and elsewhere. As for eating this person's food, it is disliked if the eater believes that most of his wealth is unlawful.