Life is about learning to pick your battles. Is it really worth spending all your energy on complaining about lack of chocolate powder?
Seriously, you're being a pedantic wank and I would think that you had better things to do with your 'principles'.
Pretty much what's already been said.
For flexibility, I guess go with places that are open longer hours. Logically, they would be more able to place your shifts around uni times. But flexibility also depends on the managers and whatnot, so it's kind of the luck of the draw
Are you in a position to be able to afford yasmin in the long term? If so, I'd say stay with it, or perhaps try a few different cheaper ones to see if you can find one with similar effects for you?
elitist coffee makers believe the milk needs to be steamed before putting it in the coffee. My mum hates this and always asks for cold milk in her coffee and she gets some weird looks from cafe staff.