It's never too early to begin thinking about all aspects of your career as a pro writer. Creating a Web site is one of them.
NOT a blog. That is an online diary. Most people use it to blather on about their personal lives, attracting no one, not even their mothers. Others use them to recount progress on favorite interests, and those are more successful, but not very. Few of us are Scalzis or Strosses - or Lindsay Lohans!
A Web site CAN include a blog if you select the right platform. But it's best to have two sites: one personal, the other professional. The blog part of your professional site should be restricted to announcements of books which have now been published, with links to where they can be bought. Both Amazon and Barnes & Noble put up the first 10% of your books for readers to sample.
You can also post excerpts of your works on your site. The blog part can then include links to those - but not the excerpts themselves. Remember that only the most recent announcements will be visible in the blog part. If you've included five important posts in it you want readers to see all five of them, and if they have to scroll down to see them most readers won't.
Remember an important fact about ANY Web site. MOST READERS WILL ONLY GIVE YOU TEN SECONDS. And if you bore them or force them to work they will skip on to another site.
As for platforms, WordPress.com is far and away superior to all the others FOR WRITERS. The next closest is Blogger, far behind WordPress. Here is why.
I should mention that I'm a software engineer of many years experience, including creating and keeping up Web sites both professionally (at Boeing) and personally. The advice you're getting in this post reflects that.
Here are the links to two of my Web sites, one pro the other personal. Both are intended to support my writing career.
Notice that even in my personal site the blog entries are short.
Finally, remember that sites are supposed to be reflections of YOU. Look at other writers' sites and decide what would work for YOU - or would not.
Here are several sites for SF/F writers. Those in Bold are WordPress sites. Notice how varied they are. Each presumably suits the unique needs of the individual writer.
http://www.theonering.net/ - J. R. R. Tolkien
http://www.keystothekingdom.com.au/ - Garth Nix
http://www.antipope.org/charlie/blog-static/ - Charles Stross
http://www.dendarii.com/ - Lois McMaster Bujold
http://www.cheysuli.com/author/Index.html - Jennifer Roberson
http://www.varley.net/ - John Varley