Need a car audio expert's advice

OK when it comes to installing/understanding the specs of car audio I'm a little brain dead.  I bought my system about 4 months back and I transfered it to my new car (an mx3 hatchback) and am rather disappointed with the amount of rattle and it just doesnt sound the way i want it to.  So if someone can recommend what I should get to finish of my set up that be great someone please help!!!

Oh one other thing I have a feeling I am goin to need a crossover, if someone could actually tell me what it is used for that be awesome, and if theres a way to avoid it in my set up that be great too.

Head Unit---http://www.futureshop.ca/catalog/proddetail.asp?logon=&langid=EN&sku_id=0665000FS10056718&catid=10174

Subs I have 2 of these hooked up---http://www.futureshop.ca/catalog/proddetail.asp?sku_id=0665000FS10040196&catid=11051&logon=&langid=EN

Amp--http://www.futureshop.ca/catalog/proddetail.asp?logon=&langid=EN&sku_id=0665000FS10040348&catid=11031

Box--http://www.futureshop.ca/catalog/proddetail.asp?sku_id=0665000FS10030843&catid=11062&logon=&langid=EN

I also have a 7 inch tv screen and my xbox running off of it but I don't think I want to do anythin with them.

Im not gonna bother mentioning speakers because the front ones are stock and the back ones are new pioneers but i cant remember the model number.

What I want to do

Speakers:

What I want to more or less do is get all 4 new speakers with all four of them being powered by an amp, now I dont know if I would need a crossover for this but I also want to have a set of tweeters or both front and back speakers what size amp and how many channels should I look at if I want use it for powering just the four speakers, and when im lookin at speakers what would be the recommended power  handling so when I hook up an amp to them they don't blow, and another thing should the speakers say power handling or rms and peak level like a sub does or does it not matter.

Sub/Amp:

I want to get a lower deeper sounding bass then what I currently have I don't want to sell my subs or amp tho but add on, would getting one more amp like the one I have cut it or would I be wasting my time having an amp per sub, the only other thing I was considering doing is also adding a bazooka tube or making a custom box to fit my 2 10s plus a 12 then just have the 2 10s running from my current amp and buy one more amp like my current one to power the 12inch sub

One other thing I have 8 gauge wires running with a 60 amp fuse, would I need to buy more wires or should I sell it all and get 4 gauge, any help is greatly appreciated im open to suggestions of any kind remember im kinda a newbie so try and talk stupid to me haha 

well actully all that writing and in the end i decided i need component speakers haha only problem is i dunno if i need a cross over, what does it do, do i need one?

my msn is eminems_toy_soldier@hotmail.com

Huh, that's funny.  My email just happens to be die_eminem_die@hotmail.com.  J/K, I actually like eminem.  A crossover splits up the different sounds to all your speakers- so that your subs play bass, your tweeters play highs, and your mids play mids.  A component set will include crossovers to split the frequencies for the mids/highs.  A 4-channel amp will also have another crossover built in to keep the bass from getting to your components, which will make them sound better.  The amp that you have is only for your subs, so you'll need to get another one for your other speakers.  And the sub amp has a crossover to allow only bass to play through your subs.