I'll try answering your questions EC, lol.
I'm not entirely sure how the suite works, I think it's the same way they created Golum in Lord Of The Rings, it picks up the movement from the person wearing it and feeds it back to a computer, where you can animate it any way you like. I'm not sure though. The green screen allows you to place any type of background behind an actor that you want.
I don't think that was Michael's mother in the video, the woman just had a similar build I suppose, and similar hair.
And yes, that really is Michael playing the mayor for the entire duration of the film. If you're not paying close attention, it easily passes you by that it is Michael. That happened to me the first time I saw it. I was shocked to know the film even exsisted and was so excited to just see it that I wasn't paying any attention, lol. But you can tell it's Michael by his eyes and even his voice, you can hear the same sort of tonality, although somewhat distorted due to the accent, and the same inflection on certain words.
And actually he did do "You Rock My World" for "Invincible", which I actually really enjoyed. But he was rushed into it and forced by Sony to do it. It wasn't his original planned single release for the album, but he didn't have a choice in the matter.
And just to add, I agree with your assesment of the film, it really does have a heavy undertone of meaning, behind all of the special effects and comedy, it goes straight to the heart of Michael's dilema throughout his adult life, dealing with people who don't understand.[/b]