Question on Oracle OEM version and plugin version upgrade

I have a OEM 12c (12.1.0.4) running in my setup in which I have registered over 70-80 databases. I see the plugin updates with versions of each target (Oracle database, MS-SQL, MySQL) and I have the downloaded the plugin updates as well. 1. My question is that can I update my plugin which is higher version than my OEM itself? 2. If yes, should I update my plugin one version at a time? Say, my deployed oracle database plugin version is 12.1.0.4 and available downloaded versions for the same I have is 12.1.0.6 and 12.1.0.7. So I should update the 6 release first and then the 7? Also how to go ahead with the update? 3. Are there upgrades for the OEM itself? from 12.1.0.4 to a higher version? If yes, how to go ahead with it? Are there any MOS if you could share? Thanks!!