For the team that keeps the gates. This page says what SmartApps put in your hands, what stays with other roles, and how a week runs.
Reads through released interfaces under a user with exactly the authorisations the app needs; writes through BAPIs and IDocs with the RETURN checked and the document number stored; write-back off per object until you switch it on.
Yes: two environments and a promotion gate is the standard; the Backbone deployment page describes GitOps promotion for the whole platform.
A screen is a filtered query on indexed columns; history at scale comes from the lake through pipeline handlers.
Tell us your role and one process; the demonstration runs the screens you would use, on data like yours.