I would like to know the following items listed on feature list, how it works and where to configure them

Allow comments per category or section
Choose the section and categories where comments should appear. Disable commenting on specific articles - everything is possible with the best comment system for Joomla - !jocomment!

# RSS-feed
Readers will be able to subscribe to the discussion via RSS.
# E-Mail subscribe
You hate RSS? Then you can subscribe to an article through e-mail.