How to find which templates are affecting a display?
First, you can easily debug everything with Devel module. Another trick that I use to inspect what tpl is generating a particular element is by adding $conf['theme_debug'] = TRUE; in settings.php. After adding that refresh your page (or clear your cache first) then use inspect element. The tpl should be visible now in the HTML source. See the screenshot below.



Here is a blog that describe on how to theme a field.

Hoe that helps.