Shell/No-Shell is a user function, not a domain function. You only need to go into the Panel and edit both users to be Shell users.
FTP will not let a user leave their own home directory, but SFTP, which uses SSH, will. These users need to use SFTP (from their FTP client) or SSH using PuTTY.
XXYou will also need to follow the previous advice on Groups.XX
[Update] There's no "mass command" you can do to do this. If these are your only other users (the two of them), then you need to go through your domains and do a 'chmod -R g rw directoryname
If you have other users, you need to create a new group, add each special person to this new group, then go through and 'chgrp -R newgroup' directoryname, and THEN do the chmod.
This type of setup is quite an ordeal due to the level of control UNIX provides.