No. In order to exchange one metal for another, you must sell the first holding and allow the transaction to settle, and then purchase the other holding. At this time, there is no direct swap available.
Cash in your account is not FDIC-insured, and it does not bear interest. Your metal holdings, however, are insured for their full replacement value. Cash in your account is held by a major bank in a Hard Assets Alliance subaccount of Gold Bullion International.