National Art convention got registrations from students from all parts of the country, of which $60$ are interested in music, $84$ are interested in dance and $108$ students are interested in handicrafts. For optimum cultural exchange, organisers wish to keep them in the minimum number of groups such that each group consists of students interested in the same art form and the number of students in each group is the same. Find the number of students in each group. Find the number of groups in each art form. How many rooms are required if each group will be allotted a room?