arduino prototype to breadboard prototype

Hello, i have finished my arduino prototype (3.3v pro mini) with mpu9250 and flash memory module.

Where i can find/learn what passive electronics i have to use ( capacitor, resistor, voltage regulator) is
there any section in datasheet (for microcotroller, mpu9250 and flash memory) where it is described what passive electronis (and where) you need ?
some pins of mcu and mpu9250 wouldn't be used, what i do with them? i just dont connect anyway, have to connect to gnd via resistor etc,?

Look on page 20 if the MPU9250 datasheet.