Notwithstanding any other law to the contrary, real estate loans and mortgages made pursuant to section 88-119(1)(D) and (E) shall be in accordance with conditions and restrictions set forth by the board of trustees; provided that the board may establish the minimum and maximum loan amounts and interest rates for these real estate loans and mortgages by motion, at any duly noticed meeting of the board. The board of trustees, subject to chapter 91, shall adopt, amend, and repeal rules having the force of and effect of law to implement all provisions of this section other than those relating to loan amounts and interest rates for its real estate loans and mortgages.