It's not imperative, but I'd highly recommend an outboard crossover. Installation is not a problem, you've just got 2 pairs of wires to hook to the speakers instead of one. If you can read, you can install some drop-ins with an external crossover.
There's no setup or fine tuning. It's just a little plastic box that'll mount to your door near the speaker. Mine are mounted up and to the left of the factory speaker location.
Taking a look at the CC/BB websites, I don't believe anything they offer can compete with the Crystals, especially with that Panasonic HU powering them. The Crystals are really component speakers configured for easy drop-in installation.
Anything beyond a 2-way coaxial is a waste. A tweeter and woofer can easily cover the entire frequency range.
