Most tweeters I have seen have the cap right on it. I changed my 4 door speakers and left the factory tweeter, and it sounds ok (my friend that owns a stereo store said there was no reason to change it, although I have considered it). The wiring to the speakers is hard to change, so I just spliced the wires to the factory harness. When I connected it to my head, I ran my wires to the factory amplifier and spliced into the wires going to the speakers-they look about 16 gauge which is adequate for moderate power.
As for the colors of the wires-PM me your email and I will send you the diagram. To change the speakers, simply pull off the cover behind the door pull and unscrew the torq bolt, then pull up the oval rubber piece on the arm rest and remove the 2 torq bolts there, then remove the push pin from the edge of the door that faces you when you open the door. After that, starting at the top front (by the mirror on the front doors) pull the panal to detach the snaps. Work your way around the entire door, then pull the buttom out and tilt it. Finally, you have to lift the panal keeping in mind that it is very tight around the top (where the seal by the window is). Rather than unplugging the harnesses, I use wire to tie the panal around the window frame so it doesnt just hang there. A single bolt holds a plastic piece to the door-remove it along with the speaker. This way, you can unplug the seaker and have an easier time removing the 4 screws that hold the speaker in place.
If I may suggest-get some Dynamat Extreme and stick it all around the inside of the door panal. It is expensive stuff, but it really makes a huge difference. I picked up a kit with 9 large pieces from Amazon.com for a little over $100. I want to use more on the outside of the door, under the panal (I was told by the Dynamat people that it will improve sound deadening from outside noise and further insulate the door so that sound comes just from the speaker itself and not all of the little openings in the door.