The mids depend on what you want for a low end. You can roughly figure their response with a program like WinISD from their specs, and their usable high end from the manufacturers off-axis SPL charts, not going higher than the frequency where you're -6dB at 30 degrees off axis.

A crossover to the sub is a must; use a real crossover, not Bass Blockers (which are fancily packaged capacitors in any event). You don't need a crossover if you're using a 7.1 receiver that has one built in.

Car audio softdomes are OK provided they have no wide mounting flanges.

An array on the center is not a good idea, as it would be too high to fit close enough to the TV screen, though an MTM is viable.