I just typed out a whole reply, but it ended up just describing my system - not what you asked, let me try
crossover - this is something that sits between the speaker and amp to filters out frequencies that the speaker should be playing, ie Low pass for a sub, High pass for splits etc...
Component can mean different things - but generally instead of splits = 2 speakers, component = 3 speakrs - bass, midbass, tweeter...
Monoblock is a powerful amp that will take a stereo signal and output a powerful mono signal (used for a sub)
Umm what else... not sure - definatly sound deaden your doors (or get it done)
i have focal splits up front, high end clarion HU, crap sony rears, low end alpine amp 40wrms x 4 (to be upgraded), and no sub
i want a JL W3V2 10" sealed ( < 1cu ft small box ) and amp to power it to finish off my system