I will probably choose coppermine as and have a question to start with, when i bridges the forum and the gallery.
If a user register to the gallery are they automagicly registred to the forum as well? And the other question if they register to the forum are they members of the gallery then? Can i set group access in my forum for what members who will be able to upload img´s and have personal albums or does i have to do that in cpg adm interface?
that's what bridging is about: coppermine's user management in being dropped in favor of the app it get's bridged with. The answer to your questions is "yes". Please read the documentation (http://coppermine-gallery.net/demo/cpg14x/docs/index.htm#integrating) before asking questions.