As I said, this is an extension to the existing Stripe payment profile. It is not a replacement, so I don’t listen to any webhook events.
As for the different subscription IDs, I have no idea. This addon exists only because I needed Stripe Checkout for my own website, and the recurring payment addition is flagged as experimental because I have no need for it at this time.
As mentioned previously, in XF 2.3 the Stripe implementation natively supports subscriptions, and this add-on will only function to allow you to choose what payment processors are enabled.