I use T-Mobile as my mobile carrier and as far as I know they do numbers 2, 3, and 4 that you listed here. I know this because I have received an SMS when I neared my 2GB of unlimited 4G data transfer. I also have logged into their site and used the app on my phone (HTC One S) to monitor my data usage. The phone app even tells you how much data was used by each app and when. It is fantastic. Could that be so hard for Comcast?