amp; 3, and own SongTowers. I don't know if a Philharmonic 2 has been built yet, but I'm pretty sure what it will sound like. For the same price as standard SongTowers, the Philharmonic 2 is an excellent deal (as long as you're OK with black cabinets).
With SongTowers, a SongCenter is an obvious choice. What are you thinking of as a center speaker if you get the Phil 2?
I know the SongTowers are an easy load to drive (any amp with at least 50 watts/channel at 8 ohms will get the job done), and suspect the Phil 2 will also be very easy for many amps. An amp as potent as the one you mentioned should very easily drive these speakers.
For a subwoofer, you should wait until you've heard your speakers in your home before you consider that.