Theme development

I need to do an "if" conditional inside the function of "theme_preprocess_field()", which can check if the page is frontpage or not.
But both "$is_front" and "drupal_is_front_page()" belongs to "theme_preprocess_page()".
Is it possible to use these 2 stuff in another function too ?

I can successfully modify a specific field in a node by using "theme_preprocess_field" function.
But can I make a different settings for the same node that is display on different page (e.g. page and page--front)?

For example,
I set the "Publishing options" of article to "Promoted to front page". Then both page and frontpage will show the same article.
I want the font color of body field that display on page to be black, but blue color on frontpage.
How can I achieve this ?

The current code I using in template.php show below

i use advanced forum and need to style comment forum edit page. What is the correct .tpl file name? I try comment--forum--edit.tpl but this does not work :/

I have an entity reference view that returns a list of unused taxonomy terms from the "categories" vocabulary. I'm using it in a user field to let users choose their category from a list of unused categories.

Unfortunately, once a user saves his category, it is also filtered from the list. Then if he saves again, it acts like he chose -none-. How can I make the list only filter out the selections of other users?

I love this site. Does anyone know what drupal theme/template it is using? I can't find it in the page source.

The website is: internqueen.com

Thank you very much! -Tim

I'm learning Omega 3 and seem to have a basic grasp on using delta/context to change page structure and the css to style.

But, what if I create a content-type and create content...how do I get that content into a region?

A block is easy...and if I create a View, then I can put a view into a custom page-type but all that just to get the content into a Region?

I'm trying to get all the basics down so surely there isn't a need to write a function or module to do this.