MSP430F249: DCO setting and wait time

Hi,

I have a question about setting the clock.

1) I would like to know how to set MCLK to 12MHz using DCO.

2) It is assumed that the DCO clock is set immediately after "Stop WDT".
Do I need to wait before setting the DCO?

3)

How is the frequency switching of DCO performed as a circuit?

Thanks,