For C24 clusters, generally what I do is just change the coding index to C08, and then reflash that as if it's a non-M cluster with NCS Expert. Sets everything appropriately, and if the car is a manual, the LCD will turn off. Though since you have an S54, it'd probably be best to leave the coding index as C24 and code the cluster as if it's a manual M3. LCD should turn off.
For the LEDs, you need the LEDs and appropriate resistors (follow the traces and you'll see where the resistors are supposed to go). The early clusters use resistors that are considerably larger than what the new ones come with. I'm also not sure if the early clusters use LEDs of the exact same rating as the new ones, so you might have to experiment with different resistance values to get the right brightness. Also pay attention to polarity, otherwise the LED won't light up.
I've found these LEDs to be the same color as stock, but they're much brighter:
https://www.digikey.com/product-deta...7-1-ND/3837595
I don't know the exact brightness value for the stock LEDs, but what I've found is using the above LEDs with a 1000Ω resistor gets them pretty close to stock brightness (though not identical). So what I'll usually do is just replace all 4 door LEDs and resistors with the new ones so that they match. And if I'm building the cluster for an M54 car, I'll use the two removed LEDs to replace the 7000 and 7500 RPM LEDs for the redline.