The ‘E Steps’ is the number of steps the motor has to perform to pull a set amount of filament in to the hot-end. This is used to determine the amount of filament/steps needed to extrude a solid bead for any printing head movement by the slicing program. It is based on the distance the hobbed bolt surface travels in one rotation, which usually is different between each bolt. Thus can be different for the two extruder heads.
The re-flash is needed to control the amount and rate of power sent into the heat element of the hot end. The buda uses a power resistor which will burn out of it is supplied the same amount of power/rate the hexagon heat element can handle. So if you forget to flash back to the taz4 code it will burn out the buda heating resistor during heating.
The unused blower wires can be ignored since they have no problem with connecting to nothing on the extruder.
But you may need an adapter depending on which hexagon connector you have, as the V1 flexy has the 4 individual connectors and some versions of hexagons have them combined into one 2x8 connector.