Is there an option to specify the number of entries shown when listing the members under Manage Classmates?
The number listed requires scrolling just to get to the bottom where you select the previous/next page. Previously one could scroll through the entire list.

There is no option for that. If, however, you need to find a particular classmate, begin typing a portion of the name into the search field on the listing page and the system will automatically select the matching classmates.