Last night's update had more quality of life changes, but also included a pretty lengthy FAQ about billing that covers a lot of questions I've gotten recently. You can always see the latest version here or by clicking the "Billing FAQ" tab on your Billing Page.
And, of course, if anyone ever has any questions about how to use the site (not just about billing!) feel free to ask any time here or by email. I'm always happy to help! :)