Rear speakers:
This is where I am stuck-
For the rear speakers, would it be better to use coaxial 6.5's or a matching 6.5 component set? Are components used for rear, or should I just go with coaxials? or is this another matter of opinion like asking "whats better, blondes or redheads or brunettes?" I would like to stay with the image dynamics brand for sq, price, and comparable output to the front channels. What would be better for the rear speakers- coaxial 6.5's or a component set?

This is actually what made me want to post this thread- THE AMP!!!!
At the car show yesterday, I talked for quite a while with the audio guru that does all the installs at the shop that hosted the car show, and I had a long list of amps that I had looked at, including amps from Alpine, kenwood, polk, precision power, RF, Cadence, audioque, and MB Quart. He pretty much shot them all down and said to go with either Audison, Memphis, or Hertz. However, the only one of these that are within my price range is the hertz HE4.1, but its still a little high in price, and it only puts out 70 watts x4, and the ctx65's are 100 w rms. Ive been told over and over that its better to overpower than underpower, and people run the ID's as high as 150-200w per channel, which I don't really want to do, 100-130 will probably be best i think, right? He assured me that Hertz's 70w x4 would be ample, but i am still not sure. He said that of any of the amps on my list, alpine is the only one that would be okay or acceptable in terms of stuff he would ever use, and cadence he has no experience with but he had heard good things.. So after reading and searching for hours for a good 4 channel amp to power the front and rear speakers, I'm between the Alpine MRX F65, a Cadence Q4000, a Cadence D100.4, or a Cadence Vegas. I started comparing stats and I have no idea what damping factor, SN ratio, or any of this actually means, so I really have no way to compare these. What would you all go with between these 4? Any input on experience with these amps would be great.

I listen to a wide range of music,alice in chains, beats antique, black sabbath, citizen cope, coal chamber, cream, deftones, faith no more, fear factory, five finger death punch, godsmack, gorillaz, jerry cantrell, joe satriani, korn, lamb of god, meshuggah, mushroomhead, ozzy, opeth, pantera, a perfect circle, powerman 5000, primus, pucifer, rammstein, red hot chili peppers, rob zombie, static x, stone temple pilots, system of a down, tool, white zombie, to name a few
I am doing a complete overhaul of the stock system in my 2005 Saturn Ion Redline series. I have a LITTLE bit of an idea of what I am doing , but I AM fairly new to this. I did do an install on my old vehicle years ago, but I didnt really know what i was doing then, and heres what I have lined up so far:

I ruled out double din head units because I am on a student budget- I would love a double din with navigation and everything, but just not enough green! So single din for now- I read hundreds of threads, everything from naga to Mckintosh, old alpines, but i wanted something with good/ decent SQ AND modern features like iPhone connectivity, etc. It was between a Clarion CZ702, a Alpine CDE-HD138, a Sony DSX-S310BTX, or a Kenwood KDC-X996. I chose the Clarion because it has digital time alignment, 5v pre-outs, built in bluetooth, pandora, the works. It was a real tossup between the 702 and the 138, the only con for both was there was no HD radio on the 702, and the 138 had no digital time alignment. I went with the 702 because I am on a budget, and from my understanding, Alpine is going to be putting out new decks in may that will allow cloud sharing of thousands of presets and eq settings, and a mind boggling array of other things, so I will upgrade to that then, but for now just the clarion, $159 shipped.

Front speakers:
There are component 6.5" stock speakers, and I decided to stay with components. I was shopping around for weeks, reading forum posts and calling local shops, and I was ping-ponging between Phoenix Gold components, Morel Maximos, Hertz, Polk MM, and Image dynamics. I went to a car show yesterday and there was some incredible work there, and so I started to look at 3 way systems, but they were too pricy (hertz=$300-$500 a set), Hertz and morel seemed to be a standard, but they were simply out of my price range, so I finally landed on the Image Dynamics CTX65cs set for $125 shipped.

To recap:

Should I go with coaxials or component 6.5's for rear speakers?

AND, which amp should I use to power 2 pairs of image dynamics 6.5's- cadence q4000, Cadence D100.4, Cadence Vegas, or Alpine MRX-F65. All of these are within my price range, just not sure which one will make the CTX's sound the best. Thanks for reading and helping!