Pretty easy question to answer. Yes the deck will make a difference. Better quality will produce better power, signals and reading strength, should also last longer.
The type of split will make a difference. Better quality will produce a better and louder sound. Splits are a good option for what u are listening too cause there isnt much base in it. Showing your max watt power isnt much of a help because the speaker will not produce that power. The rms is what it will produce. How loud do you want your system?
Running them off an amp is a good idea simply because u will get a louder and better sound like this.
My advice.. How every much u want to spend... take it all in one hit to a decent car audio shop and say this is how much i have, i listen to this type of music and i want it to be so loud that the whole public can hear what im listening too. They will be able to set u up with a decent deal and should set you up with gear that works well together.
If that isnt an option then stick with the bigger brands, read up on info (Hot4s believe it or not do a decent write up on audio gear each month) and go into the shop and talk. The more u know the better.
the technical info i cant really help you out with... ive always just gone with trial and error... hence y i am broke.