The system is set up so they forum and gallery session are shared, so logging in or out of one does the same for the other.
There is no special ways to see the image on the forum, but there are mods for Coppermine that will allow for the placement of gallery images and other info outside of the gallery itself.
I might suggest that now that you have the basics set up, you install THIS Coppermine Mod
so you can set the viewing and upload groups separately. Another mod that I have not yet looked at but might be useful is this one: Display Coppermine Data on other pages