Um.... What do you mean by speaker array? You don't need to connect two M22s per channel to get good sound. In fact, it will probably be worse. If you need more sound for your room, you should look at M50s, 60s, or 80s.
The wattage rating on speakers is inconsequential. It means only that the speaker will make sound at the bottom of the range, and will not explode at the top of the range.
A preamp switches sources (ie, CD player, DVD player, etc.) and does processing on the signal. An amplifier amplifies the signal. You need both.
No. You'd be connecting the amplifier to the pre-outs on the reciever, which bypasses the receivers amplification circuit (which is a good thing--you wouldn't want to put a 110 watt signal into a port that normally accepts a milliwatt signal!)
