I'm not using my lmce box as a router at the moment. So my eth0 is both WAN and LAN for now. Ill do a reboot and do some more tests this weekend when I have the time.
As for the actual lay out of the etwork . My cable modem feeds my wireless router that has DD-wrt on it so I can do reserved dhcp leases to an VMware esxi server easier than static IPs. This is also so when I have friends over they. Have internet without access to my media. If once supports reserved dhcp ill be glad to make some changes.
I'm pretty sure the lease time in LMCE is such that the IP addresses to clients don't change. I'm very certain I read that some where... maybe Thom said it.. don't quote me on who said it.
It would be great if you had a drawing of your network. I'd like to think you can set this up a little more straight forward and efficient than it is, at least based on what it sounds like you're doing. DD-WRT supports virtual ssids and vlans so right there you have a better network design that adheres to the supported LMCE network configuration.