time for aftermarket HU

Ok heres what i have...
-HU Pioneer Premeir DEH-P450MP
-Amp MA Audio HK-4000D
-Subs Clif Design 1200 Watt Competition 12"s (x2)

*i know thats a lot of power for those subs but i got the amp for a really good deal and if i blow the speaker i got someone who can replace them for me.

-Heres what i am going to get...
-dash kit
http://www.autotoys.com/x/cust/product.php?productid=2150&cat=0&page=1
-wire harness
http://www.autotoys.com/x/catalog/FORD_LINCOLN_MAZDA_1998_CAR_STEREO_WIRE_HARNESS_17 71_p_1354.html
-Pioneer wire clip
http://parts.pioneerelectronics.com/part.asp?productNum=CDE7060
-steering wheel adapter....
http://www.autotoys.com/x/catalog/UNIVERSAL_STEERING_WHEEL_CONTROL_BY_PAC_SWIX_p_597 .html

Now do you all recommend i buy these parts? I lost my origional wire clip from when i bought my aftermarket HU. And i want to be able to use my steering wheel controls for my stereo. Also are these the best prices or can i get the stuff cheaper from other places???

I want to get all my parts that i will need together before i start taking crap apart. I had a few questions first before i do so... I only want to AMP the subs so the other 6 speakers are to be amped by the HU, problem, HUs are meant to power only 4 speakers right? So.... how do i solve this problem... Ok Next would be how do i take off the stock HU. I was examining it closely and it appears that i need to take off the thing to get to it...? or does that hu just pop off? Next would be the CD changer... What kind of bus cable do i need to use the stock cd changer with my Pioneer Deck?
Thats all the questions i have for now. Thanks.

ok i pretty much solved most of this, figured out how to take off the center colsole and everything
got my wire harness in and the stereo harness. Got it all wired up nicely. Everything is working. 2 things left.... I didn't buy the steering wheel adapter because its too expensive for a few buttons, and i didn't get the adapter that goes from the Cd changer to the stereo. I am not sure on what that wire adapter looks like.