When are you applicable to get a replacement for an iphone 5?

I got my iphone 5 about 7 months ago and I have a 1 year warranty on it.

It's been a while and my phone has been starting to act up in ways of:

• The lock button not working unless pressed hard on the left side
• When i'm typing a message the screen tends to freeze (I tried deleting things because i thought it was caused by the lack of memory, i turned my phone on and off, but it still happend.
• It's stuck on headphones mode for a week now and i've tried everything like sucking and blowing it, inserting and taking out the headphones, turned off/on my phone, tried cleaning it with tissue & cotton swabs.
• I dropped my phone twice and there is a crack on the side (i know that it cant be replace because of that) BUT it seems like the crack is getting bigger and there is debris or something going under the glass and i'm not sure how to take it off.

How can you get a replacement online? I'm kind of scared of going to the Apple Store.

If there is no possible way of getting a replacement is there somewhere i cant get my phone fixed?