What are the WordPress plug ins that overlap with the Stack Overflow leaving comments system? In the beginning I figured about utilizing the same engine that stackoverflow.com uses. But i don't know what Content management systems or engine the after sales is running. Hence I figured I possibly could use WordPress along with a leaving comments system like stackoverflow.

Yup, here you decide to go: http://wordpress.org/extend/plugins/qa/

FTA: "Q&A enables any WordPress site to possess a fully featured questions and solutions section - much like StackOverflow, Yahoo Solutions, Quora and much more...other than better :)"

That's the lite version, additionally they provide a compensated version with increased features but which should provide you with a wise decision of their abilities.