If money and time is not a problem, then why shouldn't you? It can't hurt.
The big benefit of a personal website is that you can list all your stories there (what answers the question what you should put there ;)). So you have one page where you can link to in your e-books or mention the URL in your paper books. If the reader liked your story he can go to your website looking for more.
That means you should also link to places where they can buy your stuff like Amazon.
Additionally you should add some sort of author bio page. Depending on the legal situation of your country you maybe have to add some contact possibilities. In my country that includes an e-mail address, a phone number and the address of a real building where you live or your company resides. But Germany is very strict, so it could be less dramatic where you live. Just make sure you know what is needed.
Edit: Fiction authors and blogs
Because it was mentioned in the comments that a blog would be beneficial to an author's website, let me add, that you may not attract the audience you want with that blog.
I agree that a regular blog (one post every two weeks or more frequently, your decision) can't hurt. If it does not work, people will just not read it (same is true for books), so no real damage done (except to your ego).
But you are a fiction writer. You do not blog about photography and sell your photography books to your blog readers. You want to sell fiction. And writing about fiction to attract fiction readers is not quite that easy.
I have encountered two types of fiction authors' blogs (a third one would be a mix of both):
- Writing about writing, which attracts other authors, but not your fiction readers.
- Writing short fiction (flash fiction, whatever) to attract readers to your books.
I follow several blogs where authors write about writing. I love these blogs, yet I haven't bought one of the authors' novels.
If people like flash fiction, short stories, or whatever you can condense into a blog post, does not mean they would read your novels. So maybe posting a few chapters of the book and let them buy it if they want the rest? Maybe, but Amazon has already a preview feature.
A blog won't be easy. It needs commitment, like writing always does. If it works, you have to figure out for yourself. If you feel the urge to tell people something (whatever it is), start a blog. If you just want to do it to promote your books, it probably won't work.