Yes
a) two different squares
No. Most squares probably are not congruent. Although they are similar.
Yes.
Each has two binomial factors.
Yes
Squares and circles are always similar.
a) two different squares
Yes and No, all squares will have the same internal angels (90 degrees) making them similar, but dimensions of squares can be different (how long the sides are).
No. Most squares probably are not congruent. Although they are similar.
Yes.
Yes, all squares are similar because they are all in proportion. The angles will always be 90 degrees, and the sides proportionate. The same ratio can be created using any two side measures between squares. Thus, all squares are similar.
Each has two binomial factors.
Not always, sometimes two obtuse triangles are similar and sometimes they are not similar.
No. Two regular hexagons are always similar to each other, but two random hexagons are not necessarily similar.
All squares are quadrilaterals. Not all quadrilaterals are squares.
Two rectangles are seldom but sometimes similar. They can be but they don't have to.