Both, you can use email to send people to your blog. Let the blog contain most of the information and use links in emails to point to that information. There are even free services that allow people to sign up and get updated as soon as you post something new.
Your blog can be a relationship tool. The format lets you tell your potential clients what you’re doing and why. When you put case studies into your blog you give your prospects a story to relate to.
Blogs are search engine food. Not only are the posts optimized to provide many doorways into your site, the categories and tags increase the number of virtual pages. The end result is a very relevant site related to your industry. Keyword selection happens naturally. As you blog about different kinds of clients, and different situations, you are creating keyword phrases that the search engines can pick up.
Flexibility is one of the best parts about blogs. You can update it as often or as little as you see fit. That said, the more often you post to it the better results you’ll get. The blog is very easy to update, so mostly you just need to make time to write the posts. Additonally, as blog text is generally more converstational, you don’t need to focus in highly polished wording.
If you already have a website hosted with me, you will not need to pay any extra for hosting.