Yes. The grandparents of one are the great-grandparents of the other.
Yes. They are your First Cousins, twice removed.
Your Father's first cousins are also your first cousins, once removed.
They are out of synch by a generation. They would be first cousins once removed.
You are first cousins once removed to each other.
You and your first cousin's children are first cousins once removed. Your children are their second cousins.
The nephews of your first cousin once removed, like the children of your first cousin once removed, are your first cousins twice removed.
Yes, being cousins means that you are related.
Your son and your niece are first cousins. Her daughter and your son are first cousins, once removed.
They are out of synch to a common ancestor by one generation. That would make the first cousins once removed.
First cousins three times removed.
The children of your first cousin, twice removed are either your first cousins, three times removed, or your second cousins, once removed. Which of these relationships applies depends on which of you - you or your first cousin twice removed - are in the older generation.
Your niece and your daughter are first cousins. Your daughter and the daughter of your niece are first Cousins, once removed.