First off, I don't know the Norton firewall & I really don't understand much about port stealthing but I think you can leave it checked...you'll open whatever ports you need within your firewall anyway.
Someone else here probably knows more about this & can add to the thread if my advice isn't right in this instance

'Use UPnP' should be checked if you're using a modem/router with UPnP enabled. If you're going to try port forwarding, you'll have to check the 'Manual port forward' button & add the port number you've forwarded in the box.

When you've chosen a new listening port number, change it within the firewall config page, within your Norton firewall & also use this same number when port forwarding within your modem. Same number in the manual port forward box too.