XM Radio + adding a sub

Got a couple of questions here I'm having a brain fart on, not to mention the fact I know nothing of satellite radio.......

A friend of mine has a 97 Firebird. He's been running all stock with a delphi xm radio through an FM modulator. Well, he's lost 2 of 4 channels on his factory head unit and wants a new aftermarket. Not sure if he has volume controls, etc on the steering wheel, but I doubt he cares about it if he does.

Q#1: If he gets an XM ready tuner, can he ditch the delphi "add-on" and use the new head unit?   

Q#2: If he gets a, say 40x4 head unit (w/pre-amp outs) and a JL 300/4 amp, how can he run 2 sets of speakers PLUS a 12" sub? Is he going to need yet another amp? Seems there's enough wattage there somehow to accomodate it all.

THANKS MUCH IN ADVANCE.

1. No, but you can get a cd player with an auxillary input so you can use the rca outputs from the delphi unit and get much better sound then that fm modulator you have right now.

2. He could run the rear speakers off of the cd player (they are only supposed to be for rear fill anyways) and run the front speakers on channels 1&2 and the sub on channels 3&4 bridged (you will only get 150 watts RMS in bridged mode though so you will have to pick a sub with a lower RMS wattage but that dosn't mean it still can't get loud).

Is there any receivers that have everything built in for XM? Or do they all require the separate processor?

Never could figure out exactly how far "XM ready" went.