Read the article below and answer the following questions following contemporary Project Management guidelines and best practices:

"Poorly done projects hold up PAC's works.

So Paulo - It is not only the environmental processes that delay the Growth Acceleration Program (PAC). The lack of care in the elaboration of basic and executive projects - or even the absence of them - has also been a thorn in the federal government's side. Besides stretching the construction timetable, the poor quality of the studies can cause endless legal battles.

The reports of the Federal Audit Court (TCU) are full of reports and complaints about low quality projects, without the necessary information for the work, outdated construction techniques and inadequate values. In most cases, the ministers paralyze the works and demand new studies. This is what happened, for example, with the Port of Itaqui, an important route for the flow of grains from the North Region of the country.

The contract for the dredging of berths 100 to 103 and the construction of an area on berths 100 and 101 was suspended because of inconsistencies in the project. The Maranho Port Administration Company will need to make new field surveys and redefine the methodology for dredging and construction of the port support area.

"The project will be readjusted to the field conditions," said the administrator, noting that the studies will be completed by the end of the month. Only after this date will it be possible to define a new construction schedule. The initial expectation was that the enterprise would be ready by December 2009. Meanwhile, a good part of the producers of the new agricultural frontier MATOPIBA (Maranho, Tocantins, Piau and Bahia) have to transport their crops a few hundred kilometers to the ports of the South and Southeast."

The text mentions "stretching the works schedule" and "defining a new works schedule".

a) What information should be available before elaborating the project schedule?

b) What is the importance of a well elaborated schedule and the definition of the project's critical path?