Installation is easy. If you go the FM transmitted way, you just plug the power cord into the cigarette lighter and place the antenna on the dash. I do recommend to run the antenna up to the roof of your car/truck.
I heard today that the $30 rebate has been extended until the end of this month. This not official, but believe it is true.
I can say this much...the Circuit City here in Charlotte did a beautiful install on mine...and I'm very picky when it comes to people getting their hands on my cars. I'm sure it will vary some by location, but I had good luck with the one here.
I'm sure sirius is more on top of this than CC is. This is what sirius does, while it's just one of a hundred things that CC guy is supposed to know about...When it doubt, doubt the salesperson...