I have been working on a blog via wordpress that was setup through my hosting account for a while now.  I currently have a plugin called, Restricted Site Access 4.0 for WordPress that displays a restriction message to visitors that prevents them from seeing the actual site.I plan to deactive the plugin upon finishing but was wondering if this affects the SEO or SERP?  
Will using the production domain for testing/developing affect SERP rankings?
seo
You should install a plugin in your browser to view the status code the plugin is returning.If it's restricting access it may be returning a 403 which is not advised when you're developing a site you should return a 410 server under maintenance. This tells Google and others yes your sites there, working but under maintenance so come back later. With this they wont cache your page.Ideally though you should put up some content relevant to the final site and be working in a development environment that is not accessible at all by bots. Leaving them your main domain with the basic relevant content on your site to begin getting cached.