Ah sorry, certainly.
Firstly if you feel you can use UPnP without causing some security nightmare then just do that because with it enabled 'it just works'.
Skype has a settings/preferences page that can be accessed in the application (in the Windows and Linux versions at least). In that it specifies what port it listens for direct incoming connections on and allows you to change it if you wish. Knowing that port you can then set a port forward on WAN for UDP traffic.
The option to show info is in the Advanced section labelled 'Display technical call info'. In Windows you can also right click the video window to bring it up during a call but the Linux app seems slightly less…. polished.
There doesn't appear to be a way of limiting the video resolution. I was pretty sure there used to be a bandwidth limit you could set but if there was it's gone now. There used to be number of hacks for forcing high resolution video by editing the config file. You might be able to that to force a lower resolution. You could always use a limiter in pfSense to restrict bandwidth.
Steve