As you are doing a lot of editing and customising, this entry from the FAQ will help:
How can I find out which template to edit?
Using your browser, view the page source and look for a line of code near the top of the page which begins <div id="content" class="; the class is the name of the template. So for the main forum page, the line of code is:<div id="content" class="forum_list">, which makes the template forum_list.
That will help you identify the template should you need to edit it.
If you want to manipulate the CSS then use your browser inspector to check the code like so.
If there is a class applied to the element then you can usually hide it using display:none in EXTRA.css.
If there isn't then a template edit is required.