the factory tweeters have a built-in crossover - a single non-polarized capacitor. the door woofer wire routes from the tweeter, in parallel, with no crossover.

you need to protect the tweeter from low frequencies with a passive crossover.

no aftermarket tweeter will come with the harness to plug into the factory wire, and none will mount without a lot of modification. you can work from below and invent a mount using foams and straps. you can buy a separate harness adapter from a few vendors, Metra sells them. they are Honda specific.