(1) Under this subchapter, every warrant shall state upon its face to whom, the amount, and the purpose for which it is issued.
(2) All warrants shall be dated and shall be numbered consecutively in a record to be kept by the municipal board of improvement of the number and amount of each.
(3) No warrant shall be paid unless there is in the treasury funds enough to pay all outstanding warrants bearing a lower number.
(4) No warrant shall be increased by reason of any depreciation in the market value thereof, nor shall any contract or warrant be made payable or paid in anything but currency.