I will be purchasing the licences for this project later in the month and these will be XF, XF Gallery and XF Resources. Speaking to our IT department they did say if any of this software starts trying to hit through to the internet via the firewall they will shut the server down, I will be running it off an Ubuntu Server.
So with this said I will really need to know exactly what and how to shut off anything that might try and connect outward. I really don't need to purchase this all and find out I get stuck with not being able to use it
That seems like a rather ridiculous take on things from the IT department. They have the ability to simply prevent it from sending traffic out, so they should just do that and maybe inform you.
Otherwise, you probably need to do the firewalling yourself with the server.
I wouldn't really be prepared to give you a list of things that could make external requests as there are likely quite a few possibilities. This may change over time and things may be added in newer versions (that are on by default). Regardless, I would have to recommend blocking the disallowed requests at the server/networking level.