Ah I don't know... For me, a big part of the appeal of the AW games (besides the terrific gameplay mechanics of course! ;o) were the cute 2D sprite graphics; but maybe they could have come up with an innovative way of using the 3D depth feature of the 3DS like they did with the dual screen in Dual Strike! ;o)
When I took this picture, I hadn't made the Yellow Comet missiles yet; maybe you're confusing it with the Yellow Comet APC (between the Green Earth and Blue Moon APCs in the top row) because the trucks do look kinda alike.
I did make the Yellow Comet Missiles some time ago actually, here's a picture: [link] (you can see that the boxy truck with the black roof and the grille looks very similar to the APC ;o)
Well... the extra war room maps are... as I recall, pretty freaking easy. But, Meh you know? I remember one of them being a remake of mials hope.
Anyways, I'm going out tomorrow to by some heavy paper, and then I'm going to watch ponies, finish homework up, then try my heavy hands at some of these here tanks. Again, I can't say how amazing these things are to me man, a lot of hard work went into em'. Great work!
I'm focusing on the units from Advance Wars 1, Black Hole Rising and Dual Strike, because like you say, after that they went in a very different direction, and I don't think the new units fit together very well with the old ones.