Mmmm the ranking vs traffic thing. First of all what is your goal? Is it to have a site with high Page rank or is it to have a site with high traffic which you can make money off? Both? ... If you want people to comment on your posts you need to make your layout more enticing for them to leave a comment, maybe send them to the blog post itself instead of sending them to the home page which btw takes time to load even on a high speed connection. Also, there is nothing better for rankings than constantly updated content and a strong backlink profile... If you have a high number of visitors who only stick around long enough to click the "back" button of their browser Google knows your site might not be the best fit and thus they may cut on the amount of traffic they send your way (bounce rate) ....