if I can keep the UVerse phone and internet when switching back to Comcast for TV service? Will the 2 different services "play" together on the same wires? I would like to keep the ATT internet service so I don't need to change and update my email address.

This is why you should never use an ISP for your email address. Get a yahoo or gmail account so you won't ever have to change email addys again.

The two services aren't on the same wires.

If you are using RG6 for Uverse then you will need additional lines. In my case I used cat5 for my Uverse so the coax was available.