And what is the setup? Standard? upside down?

Those look like standard NC30 forks to me. Inverted forks have the chrome sliders at the bottom.

If you could show us a pic of the fork tops we could tell you if they are early model forks or the later ones with preload and rebound adjustment.

The tops of the forks have standard car tyre valves on them?

Standard NC24 forks. Do you have the anti-dive fitted to the fork lower?

Definitely not NC30 style. I think you are right with them being NC24. My mate used to have a CBR400 and he had this type of fork in his bike. They air valve is to add preload to the fork, but you only put in a few PSI. That is the only adjustment available on those forks.

yeah there same forks as on my nc23, i find about 10psi does the trick for handling :D

but make sure you do it with a bike pump and not a compressor lol or you will put too much in and pop your oil seals

Yeah, I've found this as well. With zero bar my forks were way too soft, they'd bottom out on every reasonably sized bump.
After adding 0.75 bar (10.9 psi) handling etc is awesome.
Yes, bicycle pump is a must. With a 50cm bicycle pump, iirc 2 pumps gets you over 1 bar!

There standard NC24 forks.

They take 8 - 11 psi.

Do not put anymore than that in there.

If you have after-market or old fork seals they won't last very long with air in them