Have hearts replaced star ratings in iOS 8.4 with Apple Music/iTunes Match? I have been rating songs for a VERY long time, have several playlists using star ratings, etc. 

You used to be able to click on an album and 'flip' it in iOS and could see the ratings of your music. This seems to be completely gone, and only have the option to 'heart' the item. Is there a way to edit the star rating of a song on iOS 8.4?
No - the controls are moved, though.

Click the song title in the now playing screen, it will change to a set of stars where you can see and change star ratings.