MSP430F5419A: LPM4.5 Mode of MSP430F5419A

Hi,

I am using MSP430F5419A for the MCU of the development. Now I need the MSP430F5419A to enter the LPM4.5 and exit from a GPIO  interruption.

I have three questions

(1) Assume that the MCU is already been in the mode of LPM4.5 and the corresponding GPIO bit is assigned for the interruption (P1.0), when the trigger of P1.0 comes to generate the interruption, the MCU will directly reboot from the beginning of the main() function, OR, the MCU will enter the interruption handler  PORT1_Isr() ?

(2) I use the following to make MCU enter the LPM4.5, is that correct? (I use the watchdog, and  timer B0 for the tick of the system)

UCS_turnOffXT1();
WDT_A_hold(WDT_A_BASE);
Timer_B_stop(TIMER_B0_BASE);
PMMCTL0_H = PMMPW_H; // open PMM
PMMCTL0_L |= PMMREGOFF; // set Flag to enter LPM4.5 with LPM4 request

__bis_SR_register(LPM4_bits|GIE);
__no_operation();

(3)Is there any approach to check if the MCU is actually in LPM4.5 but not anything else like LPM4 ?

Thanks a lot!