hanged is used when talking about people being hanged (killed by hanging). in other cases, you use hung.

insurance is noncountable n. therefore it cannot be used in plural f

as far as I'm familiar with the proper nouns, you don't make any inflectional changes when making plural form.
with common nouns, as you know, y changes into ie if a consonant precedes y.
but that rule doesn't stand for proper n.