Special code for .htaccess and robots.txt files
It looks like the most important bit they want you to put in .htaccess is this:

SetEnvIfNoCase User-Agent "^SemrushBot" bad_user
SetEnvIfNoCase User-Agent "^DotBot" bad_user
SetEnvIfNoCase User-Agent "^AhrefsBot" bad_user
Deny from env=bad_user


They should probably go inside the &lt;IfModule mod_rewrite.c&gt; block in your .htaccess file, just after RewriteBase / (whether it's commented out or not).
This RewriteBase / line shouldn't cause any problems, if your drupal site is not in a subdirectory (e.g. your index.php file shouldn't be in a sub-folder of your webroot like http://domain.com/drupal/index.php)

The Options +FollowSymLinks shouldn't need to be included twice if it's already there.