Set the excerpt characters at homepage

Hello,

I'd like to set the excerpt characters at homepage separate with excerpt characters at category page. So i asked my theme author about it, they told me i need to use this code to achive it (where the 30 is symbol count of the excerpt).

<?php echo substr(get_the_excerpt(), 0,30); ?>

Then, they asked me that i need to add to some files below:
latest-news-1.php http://pastebin.com/AUPQzv0d
latest-news-2.php http://pastebin.com/zaHG0S7z
latest-news-3.php http://pastebin.com/tS78iDyu
latest-news-4.php http://pastebin.com/VdRmRVwL

As i see at some files above, it has some code related to exceprt, e.g.

<?php
                            if($columnID=="column12" || ($columnID=="column6" && ot_check_sidebar(OT_page_ID()) == "off") ) {
                                if($columnID=="column6" && ot_check_sidebar(OT_page_ID()) == "off") {
                                    $words = 20;
                                } else {
                                    $words = 40;
                                }
                                add_filter('excerpt_length', 'new_excerpt_length_'.$words);
                                the_excerpt();
                                remove_filter('excerpt_length', 'new_excerpt_length_'.$words);
                            }
                        ?>


URL

I'm not the coder, so i don't know where is the extactly place to add the code. Please help me take a look.

Thanks,
Tuan.