Do you mean being connected to people on Linkedin and that being seen by your competitors? It would be great if you can rephrase your question but there is a hide contacts option on Linkedin.
To create blog, i would say use Wordpress. Wordpress is a content management system that is specifically designed to create blogs and other online publishing like small sites.
Its good to verify your site with engines webmaster tools as it gives you good insights into how search engines view your site. No, it doesn't hurt your ranking.