Prior to receiving any funds pursuant to this subchapter the government of Guam shall submit to the Secretary of the Interior a plan for the use of such funds which meets the requirements of this section and is approved by the Secretary. The plan shall designate an agency or agencies of such government as the agency or agencies for the administration of the plan and shall set forth the policies and procedures to be followed in furthering the economic development of Guam through a program which shall include and make provision for loans and loan guarantees to promote the development of private enterprise and private industry in Guam through a revolving fund for such purposes: Provided, That the term of any loan made pursuant to the plan shall not exceed twenty-five years; that such loans shall bear interest (exclusive of premium charges for insurance, and service charges, if any) at such rate per annum as is determined to be reasonable and as approved by the Secretary, but in no event less than a rate equal to the average yield on outstanding marketable obligations of the United States as of the last day of the month preceding the date of the loan, adjusted to the nearest one-eighth of 1 per centum, which rate shall be determined by the Secretary of the Treasury upon the request of the authorized agency or agencies of the government of Guam; and that premium charges for the insurance and guarantee of loans shall be commensurate, in the judgment of the agency or agencies administering the fund, with expenses and risks covered.