Echo cancellation is built in and enabled by default. The vast majority of the time you'll have echo or feedback in a meeting is because in one of the rooms somebody is connecting audio with their phone or laptop in addition to the Room Kit or other ...
I assume you have cold booted it (if you haven't you should). Do you have this under support with Cisco? If so open a ticket, it's likely you have a hardware problem.
No it would not. That port is designed solely for peripheral devices (the touch 10 in this case, RK plus/pro also have Ethernet ports for camera(s). It is not a switch port like you'd find on a phone or DX.
The MX700 Speaker Track system has two cameras. Go to your settings (on the touch 10) and disable speaker tracking and then switch between camera 1 and 2, my guess is one will be fine and the other has failed. If so open a ticket with Cisco for an RM...