Sorry folks, full of questions today!
Just looking at the MMB-4 kit: it comes with a single pickup, but a control plate with two volume and one tone pots. Why are there two volume controls? I guess if you could split the humbucker you might use them to control each "side" but that wouldn't seem to make much sense - and I'm not even sure if it would be possible with the stock pickup...
I've been looking at this kit as a potential build, maybe using an EMG MMCS active pickup, but that only has a single volume and tone control, so I guess I'd have to get a different control plate to avoid having to have a dummy knob fill the gap.