Hi OL,
I have similar question before and I got this very informative inputs from Relic.
You can see from the schematic how the two resistors are connected. They are wired as a voltage divider.
Yes it is a capacitor on the lower right hand. It’s for voltage/spike conditioning and retention for limited time depending on the capacitance value.
The dead end pin on the MCU is the reset and is not used.
Yes the diode is for reverse polarity and it also lower the voltage applied to the MCU by the Vf of that diode.
Maybe others can provide you inputs or corrections if mine is not accurate. Cheers! 