Ok will the circuit work as intended?

1. Input dc range is 2V-3V. Will the selected fet work for this range?
2. Whenever latch is pressed, output will be seen, and MCU is powered up. Now MCU pin is made inout high impedence.
When need to turn off, this MCU pin is made output low. This will eventually cut off the latch.
Will this work as intended?
3. Load current is only 100mA so 36ohm resistor is connected.

 

The AO3413 will be OK but you might have problems with the AM2311.

 

The NPN transistor will work as a shut-off device as long as the MCU is able to supply enough voltage to switch it on. It is not obvious if the FET will be able to adequately switch on at that voltage, so a bit of experimenting will be required to know that part. And if the MCU has momentary breaks in it's current draw there may be an issue with the FET switching off. That is something that will require actual physical testing to understand.

 

Another doubt is in schematic load is shown as R5=36 for simplicity.
In actual its "Boost + MCU", boost have input/output capacitors of 47uF each, can they can any issue?
Since they will charge in their time constant, and power will go MCU which will then wake up and put MCU pin in high impedecne?
During this time it may happen pin of MCU may behave weird?