if you are going to wrap it then leave it as is,that way you wont lose too much money!
i would fit an rst bonnet (im selling 1),mondeo 16" wheels.lower it so it sits right.as for arches,when you fit the s2 kit to a 4 door the rear doors dont open as the arches cover them,and it will fail the mot.unsure whats different with the '4 door' kit but i imagine the arch is in 3 pieces,which will make fitting a pain to get it all lined up.dont buy chrome stick on shite from halfords,dont use harnesses with standard seats as its dangerous,if you fit the s2 interior then the doorcards wont match and im unsure if the rear seat will fit on the hinges.never done this before but know the estate is different.
lastly,ill mention it again,dont buy chrome stick on crap from halfords,or anything from lockwood to accessorise the interior.
good luck,btw pics?