i want my Memphis channels, If I tell dish that i am moving would the turn the on them for me but my billig address will be in Harlingen tx. or would I be out if the spot beam
They would turn them on for you, but you are probably out of the spotbeam which means you would get the channels and the guide, but you could not watch them.
Hard to say for sure. When I moved a few years ago, they forgot to switch my locals (they knew my new billing address - they just messed up). To my surprise, my old local stations were still. But I had them switch the locals to my new city - being 2 time zones away, the timing did not always fit well.
Sling box allows you to transmitt a TV channel over the internet from the transmitter to your receiver actually anywhere in the world. You just have to have a site for the transmitter.