When running tests it's best to use the PayPal sandbox on a test environment, which would then be safe to empty CBSubs tables. For live tests it's best to do a small amount (e.g. donation plan or short subscription plan) then simply leave that data. It's not recommended to delete the data, but if you do be sure you completely cancel the subscriptions (on your site and at PayPal) before deleting.
Based off the information that was available it does not seam like the gateway is configured correctly. You received no recurring payment IPNs and you've no PDT returns at all. Maybe the result of switching to HTTPS without having a domain level redirect from HTTP to HTTPS which caused PayPal to be unable to reach CBSubs.