(1) After the provisional order hearing is held and after the board has disposed of all complaints, protests, and objections, verbal and in writing, the board shall determine whether to proceed with the improvement district and with each assessment unit therein, if there is more than one.

(2) If the board desires to proceed and desires any modification, by motion or by resolution, it shall direct the engineer to prepare and to present to the board:

(a) A revised and detailed estimate of the total cost, including without limitation the cost of acquiring or improving, or acquiring and improving, each proposed improvement program and of each of the incidental costs, which revised estimate shall not constitute a limitation for any purpose, except as otherwise provided in this article;

(b) Full and detailed plans and specifications for each proposed improvement program designed to permit and to encourage competition among the bidders if any improvements are to be acquired by construction contract; and

(c) A revised map and assessment plat showing, respectively, the location of each improvement program and the tracts to be assessed therefor, excluding any area or program not before the board at a provisional order hearing.

(3) That resolution, a separate resolution, or the resolution creating the improvement district may combine or may divide the proposed improvement program or programs pertaining to the improvement district and any other facilities into suitable construction units for the purpose of letting separate and independent contracts, regardless of the extent of any improvement program constituting an assessment unit and regardless of whether a portion or none of the cost of any project is to be defrayed other than by the levy of special assessments.

(4) Nothing in this article shall be construed as not requiring the segregation of costs of unrelated improvement programs for assessment purposes, as provided in this article.