I can’t say about MOSFET vs. FET. Without going beyond my zone. 
Surface mount devices are fine. If you are driving the hair brush vibrator (?) with the same FET, obvsly it will have to handle the max current of that in addition to the small current the control unit will need.
I am sure you do mean to test the software, somehow. I don’t think I’ve ever written something that didn’t need some fixing when it was entered and tested.
So you will need to fake the power on power off part.
Power on: that’s just reset or turn on the control unit with a switch. That’s what the program would experience with the real circuit attached.
Power off: to recognize the power off long push and prove that you have done, just use an LED and light it up to show when you circuit, if it was there, would turn things off.
I can’t leave without mentioning wokwi.com, my new favorite toy, which makes all kindsa testing much less painful than the normal cycle of development using a real Arduino.
a7