Hi
I suggest you refer TN101 of how to implement interrupt for 16bit MCU.
Vector number can be found in datasheet vector locations table.
Count from bottom of the table for the “vector number”. the reset vector is vector number 0 (located at address 0), vector number 1 is located just after the vector 0 (at address 0x2) and so on.
ie Reset = 0 (address is $FFFE), Clock monitor reset = 1, COP watchdog reset = 2 , ...... You can see “Vector Priority” in this table. When the two interrupt occurs, the system will accept the higher priority interrupt.
Have a nice day,
Jun Zhang