Best SEO Practices when Moving WordPress Installation

I read somewhere that it is better, from an SEO standpoint, to delete the Hello World post and start a new post than to just modify the Hello World post because of how things work in the background. I know publishing or updating a post re-pings services, but what else does Publishing a post do that updating a post doesn’t? What causes a new post to get listed on Google faster than just updating the Hello World post.

Secondly, does switching a post status from Published to Draft and back to Published cause WordPress to do anything different than Updating the post? Or, does the Import feature perform the publishing function or just rewrite the database?

The reason I ask is I have built a WordPress site in a testing subdomain on my local site and I need to move it to the domain where it will go live. There are about 20 posts and pages and I want to make sure any SEO functions are re-ran on the live site with the new domain.