A throw away attitude means, I think (as idioms are often not very specific in their meaning) a "devil-may-care attitude" - lackadasical, not stressed, easy, uncaring. Generally not meant critically, just an observation that the person is not as serious about life as the speaker is.
The importance of stardom is celebrity status; to expect to be treated like a (movie) star.
To be hosed is to get the bad end of the deal. Paid way too much, or made a bad agreement that was not fulflled in your favour.
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