Yes you will need to re compile your firmware to support two extrudes.
With dual extrudes is is recommended to have identical extruders, including steps/mm so a DRV8825 at 1/32 microstepping is a bad match for a a4988 at 1/16th micostepping
I would put the DRV8825 on X axis and make the E0 and E1 the same a4988's
NB if you think printing is complicated, dual extruder printing is 4 * as complicated.... be warned.
You need to create two models one for each colour, you need a slicer that knows how to do dual colour to combine the two objects, You need firmware that knows about dual extruder and is configured for correctly for it and you need perfectly aligned in Z dual hotends (presuming your using multiple hotends)