Well, first you need to pick a topic you're passionate and knowledgeable about. Then, organize your thoughts clearly and write in a simple and engaging way. For selling, you can use platforms like Amazon Kindle Direct Publishing.
Sorry, as a novel reader, I didn't visit Amazon directly or get information about 2014 book sales. However, according to some news reports and public data, Amazon's total sales in 2014 were about 80 billion US dollars, of which book sales accounted for a small portion, estimated to be about 15-20%.
It's not that complicated. You need to have a clear idea and structure for your story. Then, focus on making the language engaging and easy to understand. Amazon has some guidelines you should follow too.
It depends. Some fiction ebooks sell extremely well, especially those by well-known authors or with compelling storylines. However, there's also a lot of competition, so not all fiction ebooks achieve high sales.
The key to writing fiction ebooks is to have a unique premise. Develop the story gradually, adding depth and complexity. Edit and proofread thoroughly to ensure quality.