To answer question 1 we’d need to know more about your product. That’s why we like people to talk to us early in their product development cycle. If your situation is simple, we’ll have a simple plan to fit your needs. Otherwise we’ll create a custom plan for your product.
For question 2, an outbound event is anything that leaves the Particle Cloud as @Moors7 answered. That currently includes integrations (webhooks, Azure, Google, etc) and event subscriptions from external applications.