Benefits of using the agent and what ports?

Benefits of using the agent and what ports?

Hi,
 
I've been brought in to a new site to replace a technician who left suddenly and they're in the middle of setting up ServiceDesk Plus. It's mostly sorted and in use but I've been asked to set up the scanning and inventory functionality. We have the Windows Firewall set up and they're reluctant to open it up any more than they have to so I'd like to ask about ports first of all.
 
I've got everything I need to know about scanning using WMI from here:
 
But what is necessary to deploy the agent from the console and what does the agent actually need open itself? At first guess I'd suspect that it can open up the outbound connections and run scheduled scans without any changes but would need a port opening to prompt an on-demand scan from the console. Or am I way off the mark here?
 
What are the benefits of using the agent? Can it actually gather or more information, or do it with less ports? Or is it simply for offline scanning on laptops and such, so that the data they gather can be uploaded when it's back in touch with the server?
 
So to round things up what I'm really after is:
 
1. Ports.
 
2. Benefits of the agent.
 
I'd really appreciate any help that I can get.
 
Thanks.

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