What are the main management functions common to all managers? How these are influenced by levels of managerial hierarchy?

"To manage is to forecast and plan, to organize, to command, to coordinate and to control." - Henry Fayol.

There are five basic functions of a manager, planning, organizing, staffing, leading and controlling. 

"A plan is a trap laid to trap the future."- Allen.

Planning is the primary and pervasive function of management that is preliminary to all other functions. it regards to deciding the course of action. it merely means "what is to be done, when it is to be done and how it is to be done."
Planning includes choosing objectives, communicating them, identifying the planning premises and survey the resources. It also includes choosing alternatives and employing them, setting budgets, course of action, rules, policies, procedures, time table, and the standards.

Organizing is the second function of a manager whereby it is the responsibility of the manager to accumulate resources and dividing the activities required. 

It includes the following:
Identifying actions, dividing the activities, assigning the responsibilities, delegating authority, and keeping a thorough eye on the the way things are done.

"Staffing is the process by which a manager builds an organization by recruitment, selection and development of individuals as employees." - M.C. Farland.

Staffing is a very descriptive and elongated activity, it not only includes the recruitment of employees after determining the needs of organization, but also orientation, training, performance appraisal, promotion, compensation, and termination are a part of this function.

Leading is another major function of a manager whereby he sets rules, gives orders, supervises the staff, counsels the employees, and directs them in the way of achievement of objectives of organization.

Controlling is the last function of the manager but not the least. Controlling is required at all stages and after each and every function to ensure that all the activities are being done in the prescribed manner and paying off in the best way possible. it includes testing employee performance according to the standards set by the management, discovering reasons for low efficiency, employing people to discover the causes and factors, and finally finding out ways to better the situation and performance of the employees.