I would personally not use a subdomain but instead use a subfolder. So www.yoursite.com/blog versus blog.yoursite.com. Up until a few years ago this would be absolutely essential as the thinking was Google treated subdomains separately and therefore SEO juice didn't flow between subdomains. Today, I'm not sure if that's the case.

Still, I just like the structure of folders much more than subdomains. In my opinion, subdomains should only be used for specific reasons like completely different product lines.

This practice is quite common. Think of your blog posts as mini-landing pages. Make sure they are optimized for keywords. Make sure there's some type of call to action to get them to go where you want them to go.