Search & Replace Question (Regex?)

Question

I downloaded a government website that I would like to modify and add to my website. (It's legal, copyright-free)
But I'm finding it difficult to work with because the pages are packed with sloppy code - JavaScript and CSS outside the head seciton, tables nested in tables, etc. I'd like to get started by zapping as much of the extra code as possible.
First, does anyone know of a search and replace function I can use that would delete the entire head section in every file in a folder? Second, do you know of a search and replace function that would delete everything up to a certain point?
For example, suppose the content I want to save begins with <table myID="HomeTable"> in every file. Is there a way I could delete everything up to <table myID="HomeTable"> in every file in a folder?
Or it might be easier if I simply did a search and replace to insert a particular code. For example, I could insert XYZ or < XYZ > or [XYZ] at a certain point in every file, then use some sort of regex to delete everything up to XYZ. Does anyone know of a regex code that would do that?
Thanks.

Answer 1

No, the file names are fine. I just want to insert or replace content in the files.
For example, every file might include the code <div class="iData">. So let's say I want to insert a line of code above that...
<include file.php>
<div class="iData">
No problem; I can easily do that be doing a search and replace operation that targets all files in all folders. But suppose I want to insert that line of code ONLY in folders named Ecology.php?