Few questions on a 99 Jeep WJ build

[B.T.Smith]

Let me start off my saying, i am nowhere near the greatest, nor do i intend to make myself seem like the greatest. that being said, bear with me please.

Alright, on to my topic of discussion. I have a 1999 Jeep Grand Cherokee WJ 4.0L. This Jeep has the Infinity Gold system in it. This is where some confusion has came from. It has factory tweeters in the front, 6x9's in the front doors, and 6.75's in the rear doors (i think). it does not have cd changer, nor does it have factory subwoofer. I have searched www.wjjeeps.com and could not find any help on this. I know all the speakers are ran to the amp. ive got the basic grasp of this concept. my questions are:

1: As for the head unit, there is a single wire (blue nd Yellow i think), in a connector with just the one wire in the back of the factory head unit, i have no idea what it is for. ideas?

2: Head unit again, there is no ground in the factory connectors, it is just a chassis ground. should i cut and spice this into the Chrysler connector i have for installing the aftermarket head unit, or should i fab up a tab on my head unit and leave it as a chassis ground

3: The Infinity system... does the Infinity amp filter signal and only send highs to the tweeters, mids to the mids, bass to the 6x9's (i read that somewhere) or is it like any normal speaker system and it gets full range to the speaker but only plays so much of it?

4: My factory Tweeters are blown, and the speakers sound tolerable. but i for sure want to replace them. tweeters are 2.5"... wjjeeps.com said some 3" works. what should i do for speakers? i was thinking Kickers would be good, but i cannot find a set of Kicker tweeters for a price i am happy paying. if i have to, i will. i just want to see my other options.

this is MY first real system. i had one Memphis ten in my old truck with a small amp, just because. However, i have wired several of my friends systems and have fixed any problem they have had. I am (without sounding over-confident) very good at wiring and such. I just need some input from others to make sure i am doing it correctly.

BTW: this will NOT be an SPL build. Just looking to get a little bump in my drive to work and college, as well as for recreation. maybe one day i will have an expensive build, just not right now.

also, eqiupment i am working with:

Dual Head Unit (upgrading to a Soundstream)

Audiopipe 1000W? amp (not sure of Model, i can get it it u like)

Audiopipe 4 gauge wiring

Power Acoustik Fubar 15" (rated 1000W RMS)

[B.T.Smith]

anyone have any input? any at all? even just opinions for the chassis ground or not?