Are subwoofers pretty much the same?

[Chromatischism]

I agree; integrating a sub or two in a system is no small peanuts.
You need a good bass management system, read the proper x-over slope, frequency and phase.

Another option is DSP...Room Correction and EQ system...a good one.
Some hate that, others love it. It all depends...analog, digital, solid state, tubes.

All of the above. Placement, measurements, delays, crossovers, room EQ, and lots of listening and changing settings. It takes days. But it's worth it!