Having taught people to ski for quite a few years, MSeries is entirely correct. Modern deep sidecut skis don't require as much ankle flexion as the skis of 15 + years ago (squeeze the tomato but don't squash it), but ankle flexion will allow you to absorb shocks and the pressure increase at the end of each turn while staying centered over your feet. Bending just the knees will send your weight back over the tails of your skis, reducing control and straining your knees.
Hand and head position is similar to carrying a tray of cocktails. Look where you're going, not at the tray, and keep your hands out in front so they can lead your body.
Properly fitted ski boots can be disconcertingly snug, it is quite normal for your toes to contact the end of the boot when standing normally in them. Think of rock climbing shoes instead of bedroom slippers, and think of a comfortably loose pair of ski boots as being like loose steering on a car or loose handlebars on a bike.