The maximum clock frequency that can be used with the internal oscillator is 32 MHz.
The watchdog timer can be configured using the WWDG_CR register. You need to set the WWDG_CR[WDGA] bit to enable the watchdog timer and set the WWDG_CR[W] bits to set the timeout period.
Yes, the STR912FAW47X6 can operate with a power supply voltage range of 2.4V to 3.6V, so 3.3V is within the acceptable range.
The ADC on the STR912FAW47X6 is a 12-bit successive approximation ADC. You need to configure the ADC using the ADC_CR1 and ADC_CR2 registers, and then start the conversion using the ADC_CR2[ADON] bit.
The maximum current that can be sourced by the GPIO pins is 20mA.