Folder actions will break down when a volume is unmounted and won’t restore when mounted again. So every time you mount the volume you need to reconfigure your folder actions (Which can be done with a script). Adding and removing works over network, “opening window” folder action I’m not sure because I can imagine that the action is triggered by the Finder and not by the file system, but I’m not sure about that.
Watchpaths (launchd) is a better alternative for folder actions over network. However watchpath will only trigger if something is changed to the folder file. So reading out a folder (when someone opens the folder in the finder, or uses ls command on the command line) won’t change anything to the folder file, unless the Finder window changes the .DS_Store file again, then it will be triggered.