B, the M22 and M2 use the same mid-woofer( the M22 has 2, of course). The M3 has a different one and has a slightly depressed midrange compared with the others. You can check this on the M2, M3, M22 reviews by SoundStage which can be found at ecoustics.com and which include the NRC measurements showing frequency response among other things.
If by "full" you mean low bass, the answer is definitely not, but you said that you'd be using a sub, and that is what will supply the low bass to the other speakers.
On flexibility, understand that if you get one M2 now, you can get a second later if you want them as surrounds. Also, don't assume that you'd prefer a VP to a vertical M2 as center. Many prefer the sound of a vertical center speaker similar to the mains to that of a horizontal array. Don't be surprised if you prefer a M2 center and QSs as surrounds.
