I would measure the resistance of the factory tweeter first (Unhook one of the good ones in the car). Some of those factory amped systems have high impedance speakers. If the factory speaker is like 12 ohms, and you replace it with a 4 ohm one…that amp is going to run hot if not blow. If the speakers are close in impedance, than you should be safe.
As far as the caps go, their used for crossovers, or “bass blockers”. Again, their only going to be useful depending on impedance of the speakers. Just because the speaker might have it now, doesnt automatically mean you can switch the speaker. And unless the speaker has the same exact impedance as the one you replace it with, the cossover point isnt going to be the same.