Uverse has a 250GB cap and has had for at least a couple of years, but it has never been enforced that I'm aware of.
AT&T DSL furnished a modem but I am not sure you can even buy AT&T DSL anymore. They started arbitrarily moving those customers to Uvers a year ago or more.
Uverse uses a "Home Gateway". It's a Pace/2Wire combo modem/router and handles tv/internet/wifi & Uverse voip phone. They may have a new supplier at least in some regions.
As far as I know, no one has figured out a way to replace the Gateway with their own setup. If you want to use your own router, for instance if you wanted N wifi, you would connect your new router into one of the 4 ethernet ports on the Gateway, called router behind router, turn off wifi in the Gateway and open a port for your new router, called putting it in DMZ mode.
We've had Uverse tv and internet since the fall of 2007. We've been very happy with the service. We've upgraded the tv package to what's called U300 and the internet to Uverse Max which is 12Mbps down. Never had a problem streaming a movie or music and our 3rd party voip phone works just fine.
I've never needed another router but I do have 2 switches in use, one at my entertainment center feeding tv, audio receiver & set top box and another on my desk for those times I need more than the one port left open on the Gateway. So far, no issues.
