Hey… A slight update here… In the end I just decided to use my primary router for everything and just use a separate virtual wireless network for the home automation devices.
But I did ask about using wifi and ethernet at the same time over at Raspberry stack exchange and this is what I received:
https://raspberrypi.stackexchange.com/questions/92506/simultaneous-dual-networks-lan-wifi-setup
Maybe it will help someone.