Currently in India, Data Science has enormous career scope and job prospects. As far as your first Questions is concerned, CSE as a whole, has some deep influence of Mathematics, however Data Science will have more of Maths, Statistics, Probablity, Combinatorics based Theories to Study from. However, though Cyber Security job prospects arent that strong, with the boom of Cryptography, Crypto Currency, Cloud Computing and Cyber Vigilance, this sector will soon speed up, and secondly its a great area of Research.