in a factory system your "crossover" is usually a very Mediocre thing, a car on the tweeter and nothing on the woofer...at least in most cars. if you are unfortunate enough to have an externally amplified system the crossovers are usually in the amp.

i would probably ditch the frankenstein components and buy a new set and an amp. then you will run the components in parralell thru the x-over that comes with it, usually showing a 4 ohmn load...depending on the components of course.

as far as the 6x9's go, a nice set of coaxes will work fine for rear fil (unimportant IMO) and a sub to pick up the slack...

my personal favorite is alpine. i just got the spx177a's for my civic and i cant wait to get them in. they are really a dope set. but you just need to visit some shops and see what you like.

as far as the clarion deck goes...no comment