Iphone 6 battery issues, and cracked screen?

Iphone 6 battery issues, and cracked screen?!

Added (1). my phone has been having battery issues and by that i mean that it won't hold its charge! It will go from 100% to 70% within 20 minutes even if i don't use it, it will still drop its charge! I know this is covered by its limited warranty but i was supposed to take it to apple tomorrow but my screen cracked today so i don't know if they will still replace it or i will have to pay for a replacement phone since cracked screens aren't covered by warranty!

Buying an iphone 4s on craigslist?

I found an iphone 4s on craigslist its 60$ and it says "The only cosmetic issue is a chip" (i don't know what that is) and it says it is barely visable? Is it worth my time and deal?

Can my iPhone scree be fixed?

My friend dropped my iPhone 4s but it still worked… Then I gave it to my sister to use and she put pressure on the screen and it cracked even more. I'm worried thatit can't be fixed because I could see the inside of the phone but only from the top part of it. I can't slide orr click or anything at all do you think it could be fixed