When students re-submit their work, the original feedback from the teacher is saved. Additionally, students can indicate they've 'accepted' or 'rejected' the feedback (similar to Goggle Docs Comments).
It's unclear to me how one "up votes" an idea in this platform. Is it the star rating? Or is there another way? In my mind that should be the most prominently featured part of the UI here.
Members can show support for conversations by giving it the appropriate star rating; even better is if they also provide supporting examples for the idea. You'll find more about how the ideation process here works in the resources over at the right sidebar of this page, this one in particular: How do idea conversations work in the Canvas Community?
As the documentation notes, anyone except the author of the idea can apply a star rating to a conversation.
How do idea conversations work in the Canvas Community?
What is the feature development process for Instructure products?
How do I create a new idea conversation in the Canvas Community?