M.Sc

Yes, it's definitely valid. We accept the degrees from the UK and there won't be any obstacle in your job endeavours.
Best regards.

VIT doesn't disclose marks but ranks and you can also pay donation to get admission in MS.

Yes you can do M.Sc Mathematics in that university, but you have to appear for entrance test.

For M.Sc. In Fashion Designing candidates need to complete B.Sc. Degree in any specialisation from registered University. For most of the institutes above 50% is good enough. Though it changes as per the institute. Some of the entrance tests for M.Sc. Fashion designing are - Aditya Institute of Technology Fashion Designing entrance exam, Design institute of india entrance exam, Film and television institute of india entrance exam, IMS Academy of Fashion and jewellery Design entrance exam, IIT-D entrance exam.

In my view its better to go for MBA in IB. As the course curriculum of MBA includes other subjects relating to international trade. Knowledge of finance and marketing is also important from the perspective of business. Topic like international finance standards, banking regulations, International Marketing gets covered in MBA. So, to from a business aspect and real world scenarios MBA-IB is better option.