Expect it to be impaired, because distilled water will not absorb into the soil as effectively

Expect it to be improved, because distilled water is less variable from sample to sample.

Performance will be unaffected because the soil itself determines the conductivity, not the water.

Expect it to be impaired because distilled water doesn't have dispersed ions, which limits its ability to conduct electricity

Expect it to be improved, because distilled water is purer and will provide a cleaner, more reliable reading.

neither

linear

exponential

the sensor is poorly calibrated, if you correct the calibration, it will be fine.

the thermistor is self-heating, take another set of measurements in random order

The sensor hysteresis is a problem, take another set of measurements starting from the lowest temperature.

the thermistor is self-heating, turn off the voltage source and wait between measurements

the signal will be converted with 6-bit precision and clipped

the signal will be converted with 12-bit precision, and clipped

the signal will be converted, with 12-bit precision

the signal will be converted, with 6-bit precision