Google Sites storage limit: how can I monitor the situation?

If I understood correctly, Google Sites (free account) has a storage limit of 100 MB.Questions:

1. How do I monitor how many MB I'm using in my web site (made with Google Sites) and how many MB are free?

2. If I insert a video linking to YouTube, visible on the site (but it's on YT) is it counted or not?

Thank youC.