Yes
sometimes
Sometimes they are.
sometimes
Never
Yes
sometimes
Sometimes they are.
Parallelograms are squares is sometimes true. Squares are parallelograms is always true. Rhomboids are parallelograms is also always true. So not all parallelograms are squares but some are.
sometimes
sometimes
Sometimes similar but it depends
Never
Sometimes.
If they are congruent they must be similar.
Some parallelograms are squares - the ones which are equiangular (have equal angles) and are equilateral (have equal side lengths). All squares are parallelograms, but only some parallelograms are squares.
If they have the same nuber of sides (angles) then always. If not then never. So, overall, I suppose the answer is sometimes - depending on the number of sides.