What is the recommended way to upgrade 10.2.2 to 10.3.2?

1. Upgrade primaries and satelittes to 10.3.0a via SU, manually selecting
the servers
2. Upgrade primaries, satelittes and devices to 10.3.2 via SU and stages.

Do I need to upgrade all the devices with 10.3.0a before going to 10.3.2 or
will the 10.3.2 upgrade do this for me as long as the 10.3.0a update is
downloaded and available?

Can 10.2.2 communicate with 10.3.0a/10.3.2 backend?

Thank you