I haven't gotten to that part yet.  I just got the 2 interfaces to come up at the same time with different IP addresses about an hour ago.  I'm in a meeting right now (benefits of telework), so I still have to get the IP_MASQ set and stick a ZERO on the switch.  Its slowly coming back.  I'm just glad the whole contest ends in March!

As far as topology planned, I will be using wired ethernet for the cluster due to it inherent comparable speed, and the wireless will connect the head to the intranet.  This way, I can carry the cluster anywhere and connect to any wifi.  I pretty much want to be able to only connect from say my home Windows machine to the cluster head, with the head serving up addresses to the nodes.

What does your network topology look like?  Is one of your Pis acting as the network gateway (we call 'em "I/O nodes" in the HPC world) or do you have a separate WiFi router?