Lancer, welcome to the forum. Yes, it is a no-go. The button is there purely for decorative/historical reasons. The button point should be at the ideal point to divide your body in lower and upper half, if you button the lower button, you completely fuck up proportions.
A bit hard to tell from these pictures, but probably yes. What exactly do you mean by "suppressed through the quarters"?And I think in this combination there is not enough contrast between jacket and trousers. I'd take dark grey or cream trousers instead.Nice!