You can't tell from a last name. You would have to show that you share a common ancestor.
Your great grandmother's daughter's daughter (i.e. your great grandmother's granddaughter) is you mother, your aunt, or your first cousin once removed.
Everyone has two sets of grandparents - the mother's parents and the father's parents. You and your 1st cousin share one set of grandparents because one of your cousin's parents is a sibling of one of your parents. So, yes, your first cousin has a grandmother who is also grandmother. That cousin also has a grandmother who is not your grandmother, and, in fact, is not related to you at all.
Your grandmother's second cousin is also your second cousin, but twice removed. The twice removed means the number of generations between you. Your mother's first cousin is your first cousin once removed. If your mother's first cousin has children, they are your second cousins.
Your mother's Father's sisters, no matter how many there are, would still just be his sister. Her mother is also his mother, your great grandmother, and her son would be your grandfather or your great uncle.
This is an opinion, but in-family relationships are not encouraged.
Bedstemor = grandmother. You can also be more specific: Mormor = Mothers mother. Farmor = Fathers mother.
Grandmother in Norwegian is bestemor, BUT you can also say mormor if she's the mother of your mother, and farmor if she's the mother of your father.
Your great grandmother would be your mother's grandmother.
Can be but also on grandmother.
Thew brother of your mother's cousin is also your mother's cousin, and the same kind of cousins - first second, etc. So the question is really, "How are you related to you mother's cousin's granddaughter." Your mother's first cousin's grandchild is your second cousin, once removed.
The first cousin of your first cousin could be yourself, your siblings , or you other first cousins on the same side of your family. However, the first cousin of your first cousin could also be unrelated to you!
If your grandmother's sister was a cousin (presumably first cousin) to your husband's grandfather, then your grandmother was also first cousin to your husband's grandfather. You and your husband have a great great grandparent in common and are third cousins to each other.