1. The drive strength can be changed using the Blaster Plus Configuration utility and then loading the new configuration by an I2C master.
2. Please refer to the utility and the Blaster Plus User guide at- https://www.cypress.com/documentation/software-and-drivers/blaster-plus-configuration-utility
3. The configuration can only be loaded before enumeration and once the hub boots up, it cant be changed in run time.
As per my knowledge there is dependency of external EEPROM. DO we really need EEPROM?Can directly do changes from USB HUB?
If you are setting the boot mode as I2C slave mode, then the configuration from Blaster Plus can be saved in the proper format and loaded from an external I2C master. If however, you are setting the boot mode as I2C master mode, then an EEPROM is required to store the settings and for the hub to boot from it.
There are smaller configuration changes that can be done directly on the hub in Pin-strap boot mode but those do not include changing the drive strength of the hub. Please refer to Page 25 in the datasheet for more details.