Yes, you can use Wordpress for your blog. You can use your Impress.ly as your main site and integrate your blog in this way:
1. Open your site at my.impress.ly
2. Edit the site's content on your mobile or desktop
3. Click "Add more content"
4. Add a "Web Page" block
5. Enter your Wordpress blog URL in this block.
You can also use the Blog section within Impress.ly to create your own blog and post articles.
We are working on creating a Wordpress block. The block is still currently in beta and not ready to be released. We hope to release this block soon.