Well, assuming that the '07/ '08 design is the same as my '10:
Yes, the wires will already be there for the sub. However, the AMP won't be, so just swapping out the sub won't work unless you transfer the amp over as well. It's located under the steering column.
To check it it's wired for the sub, look for a cutout in the carpet on the pass. side of the tub, near the roll bar. Feel around behind that cutout and you'll probably find the sub wires. I never bothered looking for amp wires on mine, so you're on your own there.
As for the sat radio, you'll need the sat receiver (antenna) to go along with it. As I recall, it's mounted on the top of the roll bar and runs down the pass. side into the dash.