1. Your understanding is correct.
2. "Cold standby with all standby loads" cannot be achieved without segmentation of a single bus.
3. From the picture, it can be seen that the single busbar has double incoming lines. Each incoming line is connected through a transformer. One main and one standby are mutually backup.
4. Only one power supply can be put in during normal operation, and the other can only be in cold standby, otherwise a transformer will always run without load.
5. When there is a need for hot backup, the wiring is changed to single bus section, and the two bus sections each have one incoming line. Both hot standby and cold standby can be implemented, but an additional bus tie circuit breaker is required. For hot standby, the bus coupler plus automatic switching can realize the automatic switching of the backup power supply.