The maximum clock frequency for the MSP430F1111AIDWR is 8 MHz, but it can be overclocked up to 16 MHz with reduced voltage and temperature range.
To use an external crystal oscillator, connect the crystal to the XIN and XOUT pins, and configure the UCSCTL6 register to select the external crystal oscillator as the clock source.
The minimum voltage required for the MSP430F1111AIDWR to operate is 1.8V, but it can operate down to 1.6V with reduced performance and functionality.
To use the built-in UART module, configure the UCAxCTL0 register to select the UART mode, set the baud rate using the UCAxBR0 and UCAxBR1 registers, and use the UCAxTXBUF and UCAxRXBUF registers to transmit and receive data.
No, the MSP430F1111AIDWR is not 5V tolerant and should only be used with a power supply between 1.8V and 3.6V. Using a 5V power supply can damage the device.