Q:

How much web presence should I have?

I am getting ready to release my first fictional novel.  At the moment I have zero web presence (besides E-mail accounts).  I am considering using Amazon's Kindle Direct.
Before releasing should I create a Facebook account, and/or any other type of social media accounts?

A:

You need a website
As a fiction author you should buy a web domain (URL) as close to your nom de plume as possible. Include contact info, and a professional bio. If you want a blog or some personal pages that's ok too, but primarily treat this webpage as a professional address, as if it's your booth at a writer's expo – a little more advertising and splash, but much less personal than social media. Cat photos are probably ok (not really, but cats are sometimes a writer's companions), but not your kids' soccer match.
Have a specific page dedicated to this book, which will serve as a template for your other fiction books. As you write more books give them their pages. When the books are published you'll add links to where the book can be purchased, review quotes, a blurb or longer synopsis, and probably some artwork.
I wouldn't bother with a Facebook Page. There's plenty of evidence that it's nothing but a money scam – and that was my personal experience. No one saw any FB Page posts unless you pay for them.
If you write non-fiction, my advice is to buy a web domain (URL) for the book, and keep an ongoing blog on the non-fiction topic. People who are interested in the topic may discover the blog leading back to your book. This doesn't work with fiction, you'd already need to be famous for a random search about fiction to lead back to you.

A:

At a bare minimum, you need a central landing place to direct people to in your marketing.
The important items you want to cover are:

Title and brief description (genre, audience) of your book.
Your name.
Where to buy it.

This can be for just your book/series or for all your works.  If you only have one work now, you can set it up for that and decided later on if you want to change things.
I agree with wetcircuit that buying a domain name and hosting a website is the best choice.  Let me give you a real-life example.
My spouse's comic book series published its first issue last summer.  His co-writer had set up Facebook, Twitter, and Instagram.  He wanted some sort of marketing material to leave in bookstores, give to friends, and use when tabling.  He was thinking postcard or brochure but I urged him to ask comic book shops and they all said bookmarks.  Note that it's an e-comic only until 4 issues come out, then it will be a collected book.  But the shops were all happy to put out bookmarks even if there was nothing tangible for them to sell yet.
Obviously promotional material needs a point of contact (for big name books or movies, you can get away without that, but even they have something).  My spouse wanted to put the Facebook and Twitter links.  The problem is that those can change, they don't have information in a clear easy to find layout, and not everyone has accounts or apps for those things.
At my urging, we went to our ISP (internet service provider) and added on a new account to our existing one.  It's just $10 USD/month extra (stand-alone accounts are a bit more) and the domain name costs $15/year.  I run the website and I set it up with Wordpress (no extra cost) which gives me slightly less control over the formatting but I get a beautiful theme that automatically changes the graphics as I post new things and links up to Facebook, Twitter, and Instagram.
The bookmarks are clean and art-focused and the only contact information is the website, nameofcomic.com.  Anyone preferring social media can find us either by going to the website (where those links are prominent) or by using the domain name to search for us within an app).
To be honest, we don't get a lot of visitors to the website.  I think it's important to have anyway.  It's a central landing place and it has a ton more info than we can put anywhere else.  We include:

A listing (with quotes) to every review.
Pictures and profiles of the creative team.
Gorgeous art.
Detailed "where to purchase" info.
And, as it comes up: book signing info.

Should you have social media too?  Yes!
Do what my spouse did and wrangle someone else to do this stuff for you for free (his co-writer does social media and I do the website, general marketing, and help with the social media).  If you don't have a web-savvy spouse, co-writer, or child, hire a local teen or college student to set it up for you.  If you can maintain it yourself, the costs will be minimal.
The accounts themselves are all free and you can set up the website so that every time you post it will automatically post to all your social media accounts with a link back to the website.
Twitter is probably the most important one.  Facebook and Instagram are fine to have but not as vital.  Instagram is more if you have a lot of graphics.  I don't bother with Snapchat, Pinterest, video sites, etc.
Don't forget Goodreads.
When you have an actual book (e-book or paper), make sure it's listed on Goodreads and put information, including your website!, on your Goodread's author page.

