1) For the exclusive development process (B4i) is mandatory to register with Apple as a developer IOS? Why?
2) That is what is sought or what function this registration with Apple?
Starting from B4i v2.0 you can start developing without an Apple developer account if you use a local Mac builder with the iOS simulator.
The developer account is required for running and debugging your app on a real device.
It is also required for uploading the app to the store.