Yes they are, I get through a reflex natural whey tub a month. You can't get too much of your protein from supplements though, unless you don't mind diverticulitis.
No but along with quorn, fish and other stuff in your diet you will be fine and get your 50-60g of daily protein with no bother and with a quarter of the fat and calories.
My 50g of daily protein? What is this, a diet for ants?
Seriously though, protein should really make up (at least IMO) 30% of your total intake and if 50g (200kcal) is 30% then you're eating less than 700kcal which is far, far too little.