Study the case below and answer the following questions.

$$The Big Boss$$ company started construction business in Hong Kong five years ago and has been engaged in building construction and civil engineering projects. At present, the company has more than $500$ employees, most of them are professionals, such as engineers, surveyors, project engineering managers, etc. Management has recently observed that staff turnover has continued to rise and that recruitment has been difficult. In view of this, the management decided to conduct a comprehensive review of the company's grading structure and employee benefits. As the Human Resources Manager of the company, the management tasks you to conduct the review as soon as possible.

$($a$)$ The company has adopted the $$Narrow$-$graded Structure$$ since its establishment. In consideration of the turnover and recruitment difficult for professional staff, the management wants to develop a more flexible but within a defined framework of grade and pay structure. You are required to review the current grading structure and advice the management which grading structure would be more appropriate. $(40$ marks$)$

$($b$)$ Do you think it is necessary to recommend that management commission a consultant to conduct this grading structure review? Please discuss your suggestion as the service fee charged by professional compensation and benefits consultant will not be smaller in amount. $(30$ marks$)$