Replacing stepper drivers

I have a MKS GEN-L V1.0 board on my i3 clone that shipped w/ a4988 stepper drivers in only 4 of the 5 sockets. Now I want to add a second extruder and use the 5th stepper. Rather than get a 5th a4988, I got 5 of the newer 8825 drivers, advertised as an a4988 upgrade w/ 1/32 step resolution capability. I have assumed they are plug & play other than a possible voltage adjustment? Will I need to tweak the firmware to take best advantage or even to use them?

I am new and understand most of what is going on here, but please have patience as I still find it all fairly complicated. I have been slowly improving the mechanicals on my cheapo FLSun printer, mainly with what I've learned here, but this is my first venture into the electronics.

Thank you,
Scoot

Replacing the drivers is straight forward, but a few things are important:
Don't use the vref potmeter as reference for orientation. The DRV8825 potmeter is on the other end.
The microstepping is different: with all three jumpers in place you'll have 1/32. You'll have to double up the steps/mm accordingly.
Vref formula is different too. See here for reference.
Another advice: the DRV8825 is known to have issues at slow speeds, that's why they aren't recommended for extruder motors. But you can mix them with A4988.

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)