Permissions and groups for Node.js

I'm looking for the best way to set up Node.js apps within Ubuntu. I have set up /var/node/ to store the various Node apps just like /var/www/ would.

What I am trying to achieve, but seem to be failing:

NodeAdmins (group) has read and write access to /var/node/.

NodeUser (user) has read only access to /var/node/.

NodeUser being the user account that Node apps run under.

This way, FTP users can change any of the files within /var/node/ whilst the Node apps when they're run by NodeUser have access to all the files.

My questions:

1) Is this the correct / safe way?

2) How can I allow more than one group to have different permissions on the folder? I have used chown to set NodeUser as the owner of the group. I don't believe that is the correct way.