if it can be made perfect, there will be no need to calibrate. from the datasheet the MSP430G2231 has a typical accuracy of plus/minus 3%, at idea case it's plus/minus 0.5%. if u can keep constant voltage and constant temperature, it will be more accurate. even crystals have some drifts and for accuracy u can match capacitors or even oven control them (for temperature).
no, but u can make it happen by entering various LPM modes, for more power saving (LPM3) you will need to use VLO (or 32Khz crystal) as the DCO is also shut down.
if u really want to showcase this, u can
. inside the wh