Iptables is setup as the lmce-firewall write the iptables rules on the background.
Bridging is so far the easyest way to do this, else you need to create forward rules and change a lot of configuration files,
i'm not shure of everything will get to work that way.
there seems to be a problem with the nfs config i'm not shure where this problem is.
I check here to be shure i'm not having this issue.
Your configuration so far seems right.