Is it possible to assign classrooms to certain categories, and later select classroom for the lesson from one category. For example: foreign language classrooms, small classrooms, classrooms on the third floor, in another building, etc.

Yes, you can select the necessary classrooms and enter the name of this group of classrooms.

Later you can choose this category in “Quick selection” dropbox, and program will assign whole category of classrooms. Later, during generation of the timetable, program will select one classroom from this category (unless it is specified that this lesson needs 2 or more classrooms, then it will select 2 or more classrooms).