A performance guarantee shall contain a construction schedule, cost estimates for each major phase of construction taking into account inflation, provisions for inspections of each phase of construction, provisions for the release of part or all of the performance guarantee to the developer, and a date after which the developer will be in default and the Town shall have access to the funds to finish construction. The conditions and amount of a performance guarantee shall be determined by the Planning Board with the advice of the Public Works Director, the Town Council and/or the Town Attorney. In establishing the amount of a performance guarantee, the Town may seek independent verification of the accuracy of the developer's cost estimates or may set the amount in accordance with the amount of the contract between the developer and the contractor who will be installing the required improvements. The amount of a performance guarantee shall be adequate to cover the entire construction costs of all required improvements, taking into account the proposed time span of the construction schedule and the inflation rate for construction costs.