John, use Approve workflow event. Here you can read more: http://ez.no/doc/ez_publish/technical_manual/3_6/reference/workflow_events/approve
and take this tutorial (present your problem): http://ez.no/products/ez_publish/documentation/building_an_ez_publish_site/the_guestbook/creating_a_workflow
Can i do the same thing with the number of articles and their relevant entries.
Yes, you can define in approve event section which will be affected by approve mechanism. Lets say you have section News, someone will publish comment in this section then administrator must approve it. It doesn't matter if this is one folder or many, but everything must be around section specified in workflow event.
Check on template level, if user can create object or not then display "Post reply" button.