1) Player issue. Not sure how you expect developers to fix an issue where players don't take the time to learn their respective roles. Also, this should be a non-issue in non-savage and raid content since dungeons are easy and generally considered leveling content where people learn their roles.

2) I agree with this. No arguements from me here.

3) Player issue to an extent though some developer help would be appreciated. There should be some sort of way for mentors to police their own or a rating system for mentors based on their helpfulness.