TOC finds paragraph styles. You can apply character styles to the paragraphs as well, but manually applied character styles and local formatting will be preserved in the TOC even if you want to use a different format for your TOC listings. You can work around that by using either nested styles or GREP styles to change the formatting for parts of the text in the headings (define the basic format as part of the paragraph style).
You can set a "next style" as part of the paragraph style definition, so if you are using a heading style and you want the next paragraph to be body, you set body as next style and it will change automatically when you press enter after the heading. You do not need separate frames.