does this include just the hook or the bar it attactches to also? how long is it?

It's the bar at 50 inches long, does not include hooks (sold separately or in a kit with two shorter rails).

The bar is 50" wide. Along with the bar you need to purchase the type of hangers you need (there are various choices for hangers depending on what you type of tools you want to hang). You can also purchase end caps if you want it to look really nice (plus keep insects out). You will also need deck or drywall screws to mount the bar to the wall (assuming you have a stud wall).

It's 50' long and 4' high. It does not include the hook and you're right, it's a bit confusing.