Crossover is around 3200Hz, IIRC. All the specs will be up on the website in a few days. You cannot use separate binding posts for each woofer without changing internal wiring. The woofers are in a series wired shaded array configuration and getting it all into balance with different wiring and amps could be rather challenging. This is intended to be a pretty fully evolved design that includes very specific components to achieve its performance rather than the typical drivers, capacitors and binding posts speaker "kits" that so many companies sell. The many months it has taken to get the design to this point have been spent trying a lot of different circuits, materials, etc. I know it's fun to embellish this kind of thing with our own musings, but I would hope that builders will give the design a chance as delivered before personalizing it. That way one will have a baseline from which to determine whether any mods are a step forward or not.
With regards to using lots of amps, some may recall that a main point of this exercise was that the guys wanted me to put a speaker in our studio that would work with a single amp of modest power. I will be doing a little demo of the capabilities today, as we run the 94dB speakers with 16 watts per channel. That's 106dB peaks.