Zesty

Very much a rookie question, but I was wondering what kind of wiring accessories and such I will be needing in order to wire a RL-P15 and Cadence txa1000d to my Pioneer p5800mp? I think I already have a grasp on the tools and materials neded to build the box, but I am wondering more about wiring,harnesses, connections, terminal cups and the like. All I really know is I'll be needing a couple terminal cups, and some wire. But I really have no clue as to what. Please help me! Thanks.

Car is a 1993 Nissan 240sx fastback, like the one pictured ...notice the angle of the hatch itself? I am looking to mount (1) RL-P15. Here is my question: Would it be worth it to try and make a box with an angle that matches that of the hatchback glass, so that it fires directly/evenly into the hatch? Or do you think it would be better to just go facing straight up? I COULD fit the sub facing back except I REALLY don't want it to stick out above my back seat, which it would.....though if facing backward is that much better I am willing to sacrifice. Also, is there much difference between 2 enclosures w/ the identical internal volume, but different dimensions? Thanks in advance.