By the way, do you guys recommend that I get a pair of coaxials for the back doors or is that not necessary?
It'll depend. If you have people riding with you at times, it's probably a decent idea, or if you want the full surround, then it's good. It's not vital. Personally, I wouldn't go without it, but I'm an exception on most. A cheap pair of decent coax's is never bad though.
So, what they proposed to you - honestly, the subs are ****. Those are absolute ****. Don't go with those. Not to mention expensive as hell. The local audio shop around me will sell you a pair of kicker CVR's, the 400 wrms upgraded model, with a good box, for $350. That's way overpriced.
The head unit is pretty decent. You'd be happy with that. The components, however... I'd stay away from the rockford comps, and get a better pair. The coaxials aren't going to matter as much, but you could get a bit better for cheaper.
If I had to throw out 5.25" recommendations, I'd probably go with something like these:
http://www.woofersetc.com/index.cfm?fuseaction=product.display&Product_ID=4169
http://www.woofersetc.com/index.cfm?fuseaction=product.display&Product_ID=7077
http://www.woofersetc.com/index.cfm?fuseaction=product.display&Product_ID=2710
http://www.woofersetc.com/index.cfm?fuseaction=product.display&Product_ID=3943
Depending on your budget, ofc.
Those are products I've heard good things about, and that would be definitely good speakers. Others can throw out some other recommendations. If you want to stick with the store, look into the focal, but I'd imagine those would be a hell of an expensive purchase retail. Otherwise, there's not a whole lot of options that
I know are good. Doesn't mean there aren't, but I can't provide too many recommendations there. JL is good, but expensive. These are a bit more than what they recommended, but honestly, it'd be worth it.
Subwoofers, now... To stick with the store, I'd say look into something like the Alpine Type R's. Maybe some of the pioneer subs could be decent. Otherwise, I'd go cheaper with the rest of the recommendations here from online. Just don't get something like those kickers. -.-
The amplifier, decent, but it doesn't put out a lot of power for the subwoofer channel. You'd be much better off with two separate amps, a 4 channel amplifier, or a two channel for the front speakers, running the back coaxials off the HU, quite a few people do that - it'll save you a chunk of money, and it won't affect sound much at all. And then a mono block amplifier for the subwoofers.