Custom Post Template + Styling that Template

Hello,

I would like to create a new Custom Post Template for all the post that contain VIDEO (whether self hosted or embedded video from site like YouTube, Vimeo etc...)

Features:
1. 980px width "video-box" above the article (see picture below). The article and the sidebar will be below that video box.
2. "video box" capability to display self hosted video + embedded video code from site like Vimeo , youtube

QUESTIONS:
1) How do I style it? I mean where do I add the "css" for that specific post template that I will call "video-box".
2) As for the features what codes should I add to enable these features.And where should I add them

Hope my question is not confusing.

Regards,
Guy-Michel