(1) This chapter does not limit or restrict the manner or method of contracting for interest, whether by way of add-on, discount, or otherwise, so long as the maximum effective rate of interest does not exceed that authorized by statute.
(2) For installment loans, the maximum effective rate of interest shall: Be determined in accordance with the actuarial method;
(3) Be calculated, in the case of a precomputed loan, on the assumption that all scheduled payments will be made as contracted; and
(4) Not be affected by the prepayment of the loan, in whole or in part.