I do agree that when you’re writing the essays, try and focus a bit on how your culture impacts you. The adcom has a strange affinity for those who show more about where they come from, than those who boast about their individualistic traits.
Moreover, start the CA essay as early as possible. And put some real work into it. Think over it for days, for months - you’ll need a lot of time to write something impressive. But do not think about impressing the adcom as you write your essay - thats the last thing you wanna do. Write what you really feel.
As far as Supplements are concerned, as long as you’re not applying to Stanford, MIT, Harvard or UChicago, you should do just fine 