The Discovery Control Center does not automatically install the Discovery agent at any time. You can manually push out the agent from the Control Center but automating client installation requires additional software. You might automate client installation with ivanti tools like DSM, LANrev, and Endpoint Manager or with logon scripts/group policy. I suggest contacting support to discuss the options that make sense for you.
When you upgrade the Discovery server to a new version the clients are not automatically updated. You can update agents from the Control Center either by right clicking a group of agents and selecting Update Client Software or you can update all clients at once by clicking Tools > Update All Secure Agents.