a) the temperature range always is automotive (-PA type)
b) You should read the FAQ manual contents on ChopSync especially for the high velocity movement
c) You set the field vectors via SPI. At high velocity, interim steps gradually become skipped, alternatively, you can switch to fullstep by skipping all microsteps from a few 100 RPM on.
d) You can start from 0V, but a voltage below 100mV is not recommended for operation, due to possible noise / offsets influencing microstep performance.