I'll show you a pic of my setup for reference on how to do a low-cost, clean setup 
1000 for RCA leads, well, that sounds good if they are Stinger as promised. Stinger mai bhi kafi saray brands hein.. even though your friend claims they r branded n all, make sure to check the terminals as well as the condition of the wire, its no use buying a branded wire if its not in good condition.
4AWG is fine, although quite thick but wont give any such noticable negative impacts, and since you have a few metres spare, then coil them neatly and at a position away from the amplifier, using zip-ties or similar.
Bro dekho, theres a difference between a 'big box' and a 'good sounding box' .... sometimes smaller but well designed boxes boom louder than bigger boxes. My subwoofer box is comparitively very small to other ppl's boxes, but sounds quite good.
HPF ko 63-80Hz he rakhna better hai in ur case, since u have them hooked to an amp, and the low notes can make ur speakers flabber like hell, spoiling ur music listening experience. for low notes, consider a subwoofer. (WHen you'll see my setup you'll get ideas, i have a 12Inch Subwoofer in my alto, and my back windscreen is totally clear !)
For amp settings, u'll find many good setting tutorials here, and i prefer that its good to setup ur amp urself, insteaad of gettin it done by the shop wala., becuz u urself know what kinda music u prefer.
check the forums for tutorials, its fairly simple.
