Bi-amping generally means using separate amplifiers for your mids/highs and your woofers. This is done with "high-end" speakers and you will find this capability with some of the larger Axiom offerings. The reasons for this that I have seen are many. Some audiophile types like to power the highs and lows with different amplifiers, claiming to match the characteristics of each with the perfect amp. Some claim that the internal crossovers in speakers are inherently inferior to outboard crossover networks. Some do it because it is expensive and as far as they know $=Quality. The M22's cannot be bi-amped, at least not "off-the-shelf" so to speak. Bi-wiring means running separate wires from the same amplifier to the high and low's individual binding posts. I really don't know what the benefit of this may be.
