How does attendance work? Do profs take attendance is big classes and small also?

That depends on the class and the professor. There isn’t like a set policy about it. From my experience the big lecture class don’t regularly take attendance but they might have clicker questions or in class quizes randomly. Small classes the professor definitely learns faces and can tell if you don’t come to class even if they don’t take attendance. In order to find out check rate my professor or just go to class the first day. If the syllabus says that attendance is part of your grade, that is a good indicator it will be taken often.