the fear of nuns is called "monachousaphobia"
A gathering of nuns is called a nunnery. Or a convent.
Generally, a convent is for nuns and a monastery for monks.
A community of nuns is usually a convent but is sometimes referred to as a monastery if the nuns live a monastic style life.
It is a nunnery or convent.
Girls who were training to be nuns would be postulants when they start, and then novices. The Catholic Orders do not allow boys to be nuns or sisters.
Yes; they are called "Brides of Christ".
Sisters of Charity
According to my reference dictionary it is a "superfluity"