I have tried installing all the above plugins with JUNO. It works. The order of installation for me is -
Juno Java EE -
http://www.eclipse.org/downloads/packages/eclipse-ide-java-ee-developers/junosr1
GPE - GWT and GAE
Online - http://dl.google.com/eclipse/plugin/4.2
Offline - https://developers.google.com/eclipse/docs/install-from-zip
Android -
https://dl-ssl.google.com/android/eclipse/