The agreement authorized by §§ 9-5-210 and 9-5-220 may contain such provisions relating to coverage, benefits, contributions, effective date, modification and termination of the agreement, administration and other appropriate provisions as the State agent and Secretary of Health, Education and Welfare of the United States shall agree upon, but, except as may be otherwise required by or under the Social Security Act as to the services to be covered, such agreement shall provide in effect that:

(1) Benefits will be provided for employees whose services are covered by the agreement, and their dependents and survivors, on the same basis as though such services constituted employment within the meaning of Title II of the Social Security Act;

(2) The State will pay to the Secretary of the Treasury, at such time or times as may be prescribed under the Social Security Act, contributions with respect to wages equal to the sum of the taxes which would be imposed by the Federal Insurance Contributions Act if the services covered by the agreement constituted employment within the meaning of that act;

(3) Such agreement shall be effective with respect to services in employment covered by the agreement performed after a date specified therein, except that such effective date may be made retroactive only to the extent permitted by the applicable provision of the Social Security Act.

(4) All services which constitute employment as defined in § 9-5-30 are performed in the employ of a participating employer, and are covered by the South Carolina Retirement Act, shall be covered by the agreement; and

(5) The agreement shall include all services described in paragraph (3) and paragraph (4) of this section and performed by individuals to whom Section 218 (c) (3) (C) of the Social Security Act is applicable and shall provide that the service described in those paragraphs of any such individual shall continue to be covered by the agreement in case he thereafter becomes eligible to be a member of the South Carolina Retirement System.