Questions about John Green that are haunting me

Currently my favorite quotation by John Green


John Green is by far my favorite author. And I sure as hell know that this isn't rare and I do not even care that I am not original because he bloody deserves to be a favorite among many. 

So far I have read Paper Towns, Looking for Alaska, Will Grayson Will Grayson and now, as of ten minutes ago, The Fault in Our Stars. 
John Green is my favorite author because well after the book has been finished and has become another spine among many other spines on my bookshelves, I am still thinking about it.
The story lines of his stories are always great. They're relateable, deep and he always manages to tell the story with humor and I laugh but I also sometimes cry.
But it is not his well thought out characterizations and story lines that leave my mind dwelling on the novel after it has become an ornament of decoration in my bedroom; it is the quotes that he comes up with that are so relevant to both the story but to life as well. And you can tell that he is a great observer and he understands so much that I only hope that not only can I manage to come up with a string of words that mean so much and sound so beautiful, but I want to tell everyone, as if hearing these particular quotes will bring peace and a greater understanding in the world. 

I know that is greatly over dramatic but my heart does not know the meaning of calm. 

After watching the movie I promised myself that I would never read The Fault in Our Stars with the intention of not putting myself through something that sappy again but after finding it on sale at a second-hand shop for $3.00, I convinced myself otherwise. And I enjoyed it. 

Anyway, these are the questions I have found myself wondering after reading these books and John Green, if you are reading this and can give me the clarity I need right now, or if anyone else can provide hints or anything, please do. 

1. Pretty much all of John Green's novels include the theme of depression. And most commonly, depression is felt by the love interest in the story. So, was there a period of time in John Green's life where he felt depressed, or, like I suspect, did he love someone who did?

2. If John Green loved a girl with depression, and I may be pushing myself here, but I have noticed that there has never really been a happy ending for the depressed, so I wonder, did he manage to help them?

3. Dark Black Blue nail polish has been mentioned three times I believe within his stories. It isn't hard to tell that he fell for someone who wore this exact color nail polish so I wonder now, was the dark-black-blue-nail-polish-wearing-girl his wife? 

4. From noticing another similarity within his novels I lastly wonder, did his youth and adolescent commonly involve pranks or anything that required planning and master-minding in order for it to follow through? 

I highly doubt to receive the answers to any of these but for once Google has let me down.