Ask the dealer if that Adrenalin has the factory subwoofer behind the driver side rear seat... if so, you're starting off with a great system. The factory system with subwoofer sounds really good in my '10 Adrenalin. I had an '08 Explorer with the 5x7/6x8 Infiniti Kappa's that I put into my '10 STA with no fitment problems. The Explorer/Sport Trac factory speakers are all the same size, 5x7, up to 2010. But most aftermarket speakers have several screw hole options to fit both 5x7/6x8 mounts.
The factory speakers sound good because they are in a sealed enclosure. But swapping out the factory speakers will generally give you better mid's and high's until you crank it up, then it distorts. So you would need an amp on those Alpine's if you want louder and clearer.
Also, be sure that you tie down the wire clip so it doesn't interfere with the window roll down, it's a little tight behind the speaker.