Hyphen in compound adjective (or not)?

[Nordic Bill]

With regard to school exams where no dictionaries, notes, etc. are permitted during the test. Would you refer to these as "closed book exams" or "closed-book exams"?

Thanks,
Bill

[Tdol]

I'd hyphenate there to join the two into a single unit.

[Kant]

How about these? Please tell me which is correct, with or without the hyphen.

1-1. They cruised the world in a run-down boat with no engine.
1-2. They cruised the world in a run down boat with no engine.

2-1. She's the most talked-about film star in Hollywood.
2-2. She's the most talked about film star in Hollywood.

Thank you very much.

[Casiopea]

If there's ambiguity, then a hyphen is warranted. If in doubt, check your dictionary.

[Kant]

Thank you very much.