(a) The board shall hear and consider the petition and may add to the district the land described in the petition if it is considered to be to the advantage of the petitioner and to the existing district.
(b) If the district has bonds payable in whole or in part from taxation that are voted but unissued at the time of the annexation, the board may issue the voted but unissued bonds even though the boundaries of the district have been altered since the authorization of the bonds.