What does the Iphone 5 warranty cover?

I dropped my iphone 5, but only on the corners and there is visible damage. Recently my lock button has been malfunctioning and only the left side of the button works. I was wondering if they will still replace my phone after this. I've read up on the "issue" and most people with this "issue" say they walked in and walked out the next 5 minutes with a brand new phone. This makes me think will they not replace it if it's my fault that is probably doesn't work.

Added (1). Also if i they will fix it, should i schedule a genius bar appointment or just walk in?

They will fix it