(1) Upon receipt of a petition or upon determination of the township board if a petition is not required under section 3, the township board, if it desires to proceed on the improvement, shall cause to be prepared plans describing the improvement and the location of the improvement with an estimate of the cost of the improvement on a fixed or periodic basis, as appropriate. Upon receipt of the plans and estimate, the township board shall order the same to be filed with the township clerk. If the township board desires to proceed with the improvement, the township board shall tentatively declare by resolution its intention to make the improvement and tentatively designate the special assessment district against which the cost of the improvement or a designated part of the improvement is to be assessed.

  (2) The township board shall fix a time and place to meet and hear any objections to the petition, if a petition is required, to the improvement, and to the special assessment district, and shall cause notice of the hearing to be given as provided in section 4a. The notice shall state that the plans and estimates are on file with the township clerk for public examination and shall contain a description of the proposed special assessment district. If periodic redeterminations of cost will be necessary without a change in the special assessment district, the notice shall state that such redeterminations may be made without further notice to record owners or parties in interest in the property.

  (3) At the hearing, or any adjournment of the hearing which may be without further notice, the township board shall hear any objections to the petition, if a petition is required, to the improvement, and to the special assessment district. The township board may revise, correct, amend, or change the plans, estimate of cost, or special assessment district.

  (4) Property shall not be added to the district unless notice is given as provided in section 4a, or by personal service upon the record owners of the property in the entire proposed special assessment district, and a hearing afforded to the record owners. If a petition is required because property is added to the special assessment district which makes the original petition insufficient, then a supplemental petition shall be filed containing sufficient additional signatures of record owners. If the nature of the improvement to be made is such that a periodic redetermination of costs will be necessary without a change in the special assessment district boundaries, the township board shall include in its estimate of costs any projected incremental increases. If at any time during the term of the special assessment district an actual incremental cost increase exceeds the estimate therefor by 10% or more, notice shall be given as provided in section 4a and a hearing afforded to the record owners of property to be assessed.

  (5) Railroad companies shall file in writing with the secretary of state the name and post office address of the person upon whom may be served notice of any proceedings under this act. After the name and address has been filed, notice in addition to the notice by publication shall be given to the person by registered mail, or personally, within 5 days after the first publication of the notice. An affidavit of the service shall be filed by the township board with the proof of publication of the notice.