I just parked my car under the garage for 1 hour.

I then unbolted the power steering pressure line nut - no power steering fluid leaked out?

Is this just purely an air pressure valve? or is fluid suppose to come out.

I'm trying to locate a leak.

Then unscrew the cap off the top of the power steering pump (the one that's labeled "Do not overfill" in yellow letters), if no oil is seen on the stem. It was empty. And that's not good.
Time to hand it over to a specialist that deals in power steering pumps/rack etc.
If it's empty, and doesn't hold oil. Do not drive it that way, or you will destroy the pump and power steering rack?

I have been topping up the tank (so it's not empty) and tightening the pressure line nut for now.

I've also been wiping away fluid from the alternator.

I have yet to locate the leak.

Yeah maybe i'll need to take it to a specialist

I pulled out the pressure line connector today.

Does the black seal around the connector look worn out?

And is this the o-ring?

See photos below (sorry for the bad quality photos, it's the best camera i got)

Correct me if I'm wrong people. But if you were to take this hose out like that, wouldn't that cause the res to fully empty it's contents?