Can I replace my ATT Uverse Router with this router
My ATT Router has a connection for the ATT Cable coming in from outside. This router does not have that cable connection. Is that cable necessary?
Generally speaking you can't replace ATT devices with off the shelf routers like this. The ATT device in your house is also a modem, if I were you, I would research the difference between those 2 things and ask ATT if you can provide your own devices because there are modem/routers that you could theoretically replace it with, however some ISPs will still not allow you to do it (its part of their contract).