I am trying to create a separate product-listing display for the Documents General product type. My preferred method would be to copy the product-listing files (tpl_index_product_list.php, tpl_modules_product_listing, and if necessary even product_listing.php) and customize them to process Documents General requests in the particular way I want. That's easy enough, but for it to work I need to modify the file that calls them in the first place so that it redirects Documents General requests to the custom files. Unfortunately, in my ignorance, I just can't figure out which file calls tpl_index_product_list.php. I would expect it to be the same file in which the switch "Skip 1-prod Categories" get processed, since that switch performs a gate-keeper function similar to the one I want to add, but I can't manage to find that one, either, since I don't know what the switch is called outside of the Admin interface.

I've spent hours doing every search I can think of, both in Developers Tool Kit and on this site, without success, driving myself to such a point that I'm actually willing to ask for help (!).

So, to boil this down:

1) which file does call tpl_index_product_list.php;
2) is that even the file I need, and if not, which one is;
3) is there some handy online resource I have somehow overlooked that would have answered this question for me without bothering all of you?

Many thanks!