How to Blog on certain pages?

You might want to read this, https://codex.www.ads-software.com/Pages

is there any plugin or something that could enable adding comments? and thus, indexing my site even more so I crawl up the PR.

You can do a search on adding posts to pages. There is some information out there but it is difficult and really defeats the entire wordpress concept.

You can add a comments option to pages when creating a new one or editing an existing one in the dashboard.

There are lots of ways to add posts to pages but the easiest is probably to create a new php template with the name page-slug.php replacing the word slug with your actual slug (e.g. page-news.php).

Replace the normal loop query with:

<?php
//The Query
$paged = (get_query_var('paged')) ? get_query_var('paged') : 1;
query_posts('posts_per_page=5&cat=000&paged=' . $paged);
//The Loop
if ( have_posts() ) : while ( have_posts() ) : the_post();

?>

Replace the 000 in cat=000 with your actual category code. You can also change the number of posts per page.

A good template to base your new one on might be archive.php.

HTH