I highly suggest downloading and reading through the CBSubs Manual below as it already explains how to send various emails.
www.joomlapolis.com/downloads/documents
There's several emails you configure under the Presentation tab of your plans to deal with emails on renewal, etc.. You can also configure more specific emails using CBSubs Mailer.
Typically payment receipts are best left to the payment provider. Both PayPal and Stripe can email users their payment receipts.