If you're root, you can't and don't want to do that across NFS shares. If you're a regular user, match up GIDs and UIDs for all users on all boxes.
Difference between NFS and Samba is protocol and interop. You want Samba usually when you want to do file sharing among Linux and Windows. NFS is the way to go for file sharing between Unixes. There's a PET on making windows play with NFS.