[harsh]

What kind of RG6 cable should I use?

Look for a solid copper center conductor and sweep testing to at lease 2.2GHz

How many cables will I need to run?

There will likely be a switch involved if you have your heart set against a DVR. You'll need to run a cable from the switch for at least three receivers and a cable from one receiver to the fourth TV.

I plan on running them to a central point close to where my present dish is located?

Don't get the cart before the horse. Not all the runs go from the dish to the TVs. You'll need to know the receiver configuration before you can wire anything.

What satellites will I have to be able to "see"?

You will need to see 110 and 119 for the standard programming. Depending on where in PA you live, you will need to see either 61.5 (Eastern PA) or 129 (Western PA).

A zip code must be known to give a more detailed answer about orbital slots required.