Where should the dhcp helper or server address be put on? You can either put on Interface or WLAN, is there an operational impact depending on which one you choose?
DHCP address should be entered in the dynamic interface. DHCP override is used if you have another dhcp server other than what you have configured in the interface you want to use. So since you can configure a primary and secondary on the dynamic interface, why would you set it on the WLAN SSID? Unless you have issues with your dhcp server and want to test or use antoher dhcp server.