To be honest mate, as long as you have a good grounding in English and maths, the airlines aren't especially interested in what subjects you take. They are far more interested in your flight training and command potential.
The lifestyle varies from airline to airline and from shorthaul to longhaul, since no two people are the same, it's very difficult to say what the lifestyle is like, because what suits some people would be the next persons nightmare.
The days of full sponsorship is sadly gone for good, however certain airlines have started to pre-select candidates prior to them commencing flight training. Places on these kind of courses are fiercely competitive. The majority, myself included, fund the training themselves and apply to airlines once qualified.