Student and Course Relationship - Grade and Attendance
As the student's grade is logically tied to both the student and the course, Student_Course is the best place to put it.

For attendance, you would indeed use a query. You can't generate the attendance sheet from one table. You're starting from a professor and/or course name, and need to get data out of the Student table. I suppose you'd need to have some way to connect the professor to the students. In the query, you'd need to find a way to tie each of the tables together. I'd check the documentation for your database, and see if it mentions any way to join tables together in a query.