To exclude category in wordpress rss feed.
you can simple write.
<a href="<?php bloginfo('url'); ?>/feed?cat=-1&cat=-2">(RSS)</a>
or you can simple write below code in your theme function.php
to exclude category categories.
function excludeCat($query) {
if ($query->is_feed) {
$query->set('cat','-1');// for multiple use with , eg- -1,-2,-3
}
return $query;
}
add_filter('pre_get_posts','excludeCat');

You have tested it and writing form your personal experience or you find some information online?
Yes i have tested it.
I would appreciate more visual materials, to make your blog more attractive, but your writing style really compensates it. But there is always place for improvement