If the course material is familiar to you it may take less, if the course material is unfamiliar it may take more. Obviously students have to balance the time spent studying with their other commitments, e.g. work, families etc. Typically most students complete within three years, but it is entirely up to you. There are no entry examinations to take to enter the MBA programme, it is enough to purchase the courses. There are no 'fees' as such.
Payment is made by purchasing the course materials.
In addition there is a fee for registering for the examination for each course. Each course has a unique serial number, and only one student may sit the examination for each serial number. It is not necessary to buy all the courses at once, but buy as you study. Most students buy one or two at a time, and complete four courses a year. However, some buy less and some buy more.