Cousin
Your cousin in law
Your uncle's grandchild would be your second cousin because his grown son or daughter would be your first cousin.
Your son is your uncle's grandnephew. Your uncle is your son's great uncle.
That would be your cousin, honey. Just keep it simple and call them what they are - family. No need to complicate things with all those fancy terms.
Your uncle's son is your first cousin.
It means you have (or had) at least two uncles and at least two great-uncles, and that is all it means.
Your uncle/aunt's son/daughter is an adult and you are still small, your uncle/aunt's daughter had a child, and that child will call you uncle. Uncles/aunts are your dad/mom's siblings.
your uncles son is your cousin
His great uncle
great uncle
Yes. Any son or daughter of Zeus would be her half-sibling. Any son or daughter of Poseidon or Hades would be her cousin as Poseidon and Hades are her uncles.
I call them my uncles