The rough sequence is

• get grade_tree tree structure for the view
• get users for this view (course, group, category, page, graded roles)
• get grades for this view and these users
• get total count of users for all pages in this view (for paging)
• get sum totals for all pages in this view
• get sum totals for all users in the course

Display everything in one table with controls and paging.