I'm not sure if anything would be different with your satellite t.v., we have cable and our internet is also cable, having Vonage didn't effect any of that at all.
I don't think that you'll be able to keep your same number. We had just our cell phones before Vonage so I didn't have to deal with disconnecting old phone service. I do know that our local exchage is 676, we have the same area code as everyone else in our area but our exchange is 666! I wasn't exactly thrilled with that, lol! Not because I think our number is cursed but everytime I give our number to someone else I usually have to think of a witty reply to "ooooh, 666".
But no, it doesn't cost anyone else anymore to call you than they normally would if they are calling you from out of your area. My comment about area codes was to say that if someone calls you long distance all the time, it will save them money if you make your telephone number have their area code. The downside of course would be that local people would basically be calling long distance to call you. I've heard that you can add a second line very cheaply with Vonage so you could do that for your second line and still have a local number for your 1st line.
Whew, I hope that made some sense!