In determining the amount of bonds to be issued, the legislative body may include:
(a) All costs and estimated costs incidental to or connected with the acquisition, construction, improving or financing of the enterprise.
(b) All engineering, inspection, legal and fiscal agent’s fees, costs of the bond election and of the issuance of said revenue bonds, bond reserve funds and working capital and bond interest estimated to accrue during the construction period and for a period of not to exceed twelve months after completion of construction.