2. Well this is not available as of now .
a. but you can have parents to login with the student credentials to check what homework(assignments and quizzes) their children have to do .
b. Well in assignments teacher can leave notes while evaluating the assignments .you can use that feature for the notes for student progress .
refer :
https://www.youtube.com/watch?v=qkr6ClILmhs
If you want proper implementation of this then please create a feature request for this here :
https://wplms.io/support/forums/forum/general/feature-request/
3. You can us ethe Buddydrive plugin for this .As it is not working in the course properly you can use it in course groups where you can attache any file using it and only course group members can access it .
Just connect a group to your course (it should be a private group) .In the group goto activity .There you can share any update and also the files through buddydrive .
refer : group creation :
http://prntscr.com/d00rxo
file sharing :
http://prntscr.com/d00sp9