Password generator and membership

I am developing a site that sells online classes. I am hoping to find a plugin that will do the following:

1. The user selects a class they want to take and clicks a purchase or register button.
2. They are sent to a window to purchase the class they have chosen.
3. When they fill out the personal information and payment information, once the payment is confirmed, an email is generated confirming the purchase AND the plugin generates a password for the purchaser to access the class they purchased and the password is also sent with the email (or, for that matter, in a separate email).

Are there any plugins that will do this or something similar?