How to use WordPress functions outside of the blog

Hello guys! I have developed an free video script called Zubee Tube and I wanna use WordPress functions in it.

My question is : What do I need to call in my script to use user related functions from WordPress in my script?

Like if user is logged in show comment form.

I need to pull the session and I don’t think that

equire('blog/wp-config.php');
$wp->init();
$wp->parse_request();
$wp->query_posts();
$wp->register_globals();

it’s enought!

Anybody can give me some tips or some links to some articles that could help? I got more than 500 persons waiting for an user system, and I think wordpress is the coolest cms to use, also using P2 theme they could make a small social network inside the video website. This could be great dont you think?

Thank you for your time in helping out!