The maximum clock frequency of the MSP430F5438AIPZ is 18 MHz.
To configure the MSP430F5438AIPZ for low power consumption, use the low-power modes (LPM3, LPM4) and adjust the clock frequency, disable unused peripherals, and use the Power Management Module (PMM) to control power consumption.
Yes, the MSP430F5438AIPZ can be used with an external crystal oscillator. The device has an internal oscillator, but an external crystal oscillator can be used for more accurate clocking.
The MSP430F5438AIPZ can be programmed using the Texas Instruments Code Composer Studio (CCS) integrated development environment (IDE) or other third-party development tools.
The MSP430F5438AIPZ has 256 KB of flash memory available for program storage.