1) I believe if it's all linux, you're looking at setting up NIS
. If there will be any other OS's attaching, you'll probably want to go with LDAP of some sort, either through Samba or openldap.
2) No idea. Network shares are typically handled through NFS, but I'm not sure you can create a network LV. You could just create one NFS share that all users could access though.
Other options you could do would be to have a central server and a bunch of thin clients.