Ph.D

Selection of the subjects depends on your interest in which area you wish to do you research and make a career. PhD duration is 5-6 years.
The exact length depends on how much time you must spend on your courses, exams, etc.

Dear Deepak,
UK Ph.D stipend varies. Don't expect funding from too many universities, most programs are funded by the students themselves with only 10% to 20% of the fund being provided by the universities. You may expect around GBP1200 to 1800 per month if you have been depending on the university.

It will depend on the subject you choose to do Ph.D in. In most of the institutes, the eligibility criteria to gain admission to a Ph.D in Management is Master's degree with 55% marks. In some subjects, doing a Masters in Philosophy (M.Phil) is a prerequisite to start the Ph.D. For some prestigious universities, it is required to qualify All India Level Examination such as National Eligibility Test for Lectureship (NET) conducted by University Grants Commission (UGC), Graduate Aptitude Test in Engineering (GATE), and Indian Council of Medical Research (ICMR).
Fee differentiates from college to college.

After your M.Tech, your entry cadre will be that of Assistant Professor. You can make a career progression to Associate Professor and Professor later on with experience if you have a Ph.D.