It is impossible to say; there are more than 30 songs by that title.
The song by George and Ira Gershwin is in the public domain; certain arrangements, performances, and recordings may have their own rights.
Not necessarily; it varies from state to state.
No; it will be protected until 70 years after the songwriters' deaths.
No. The original music and lyrics are credited to José Fernández Diaz with a date of origin of 1929. (see attached link)