yes
The hyphen would be located between the mid and the century.'Mid-century'.
Mid forties
Yes. The prefix mid- is hyphenated when it is used with numerals or written-out numbers. For example, the mid-twentieth century.
No, in general it is not correct to hyphenate certain prefixes, co-, pre-, mid-, de-, non-, anti-, etc. You therefore write preordain instead of pre-ordain, antidote instead of anti-dote, and midnight instead of mid-night.
She is in her mid or early forties
Can you, or should you? You can hyphenate it if you're moving between lines in a paragraph and need to break up the word. You shouldn't hyphenate it normally.
McCarthy should not be hyphenated.
not required
A hyphen is not required.
Yes it should be hyphenated.
Early to mid-forties is NOT an old age to have children.