(a) The commissioners shall study the plans for the proposed improvement and the cost of the same. They shall then go upon the lands within the district for the purpose of determining to what extent and in what proportion the lands affected by such project will be benefited accordingly. They will apportion the cost of the proposed project, including the cost of maintenance, for a period of not more than twenty (20) years among the lands benefited; except that maintenance costs shall be provided for throughout the period during which the credit of the district is pledged, or special assessments or taxes levied for the use and benefit of any project.
(b) The commissioners shall report their actions in writing to the court, and in the report they shall set forth in detail their conclusions and findings, listing the lands benefited by the names of their owners, acreage and description and the lump sum assessment for benefits against each tract of land, if such assessment were paid in cash, and also, the amount of the annual assessments required upon each tract, if the cost is to be defrayed by bonds or other obligations of the district for the period of years over which such bonds or obligations are payable. The proposed assessment shall also include interest and other costs in connection with such bonds or obligations.