The Pi-hole IP address is set to 192.168.207.121, but queries against that address do not resolve. What is the result of dig flurry.com @192.168.207.121 from a client or from the Pi-hole device?
Take a look at /etc/dhcpcd.conf and see what the static lines show as should be the address for the Pi-hole. And then check /etc/network/interfaces to make sure that the interface is set to manual. Finally, check ip -4 address to see if the IP address is dynamic or static. It sounds like the device is still acting as a DHCP client even though it should be statically assigned the address.
I am unable to run any of the commands you suggest, none of them are recognized with either "sudo" or "nano". What are my options from here? Is it best to re-image my SD card and start over?
If this is the case, run pihole -r and reconfigure the device to use the IP address you would like. Looking over your debug log shows issues with lighttpd as well. My suggestion at this point is to just start over, flash a new SDCard with Stretch and install from there.