There was some feedback we got about the Perfherder compare view from a few of our users (developers only) during the TH UX research project. We didn't focus on Perfherder feedback too much since it wasn't our primary focus, but there a few areas that can be worked on.
Regarding 3 from above, Cam and I focused on improving Push Health and making it a developers view. So any changes regarding improving access to Perfherder from Treeherder/Push health, let's coordinate on. See bug 1642786 for more details.