dont need but would recommend 5 stud all round for the bigger brakes and wheel fitment, but like I said not a requirement, can use r33 rear hubs with handbrake setup and r33 cable, s14 front hubs and lcas (widens track a little though) with skyline brakes all round, just for a bit of wank factor, r32/A31 crossmember, r32 steel engine mount brackets I slotted mine so engine sat right back and as low as poss as bonnet hits throttlebody, gearbox yoke off skiddy, bigger radiator, couple of 12" thermos and get rid of A/C...I could keep mine cool with a/c but couldnt use it at all, much better now that its gone. also need to make up a gearbox crossmember...pretty easy really just probably will have a few teething issues.
Thats just off top of my head, been a year or so since I done mine, plenty of threads already on it though so a search should turn up some stuff, on here or nissansilvia (although ns doesnt seem to have very good info on it, full of f**kheads)
as for price try and add up all parts
prices are gold coast prices
mount brackets $100 per side
crossmember $250
rear hubs and adapter for cable $330
front hubs lcas approx $200 I think I got them for
R32 GTR brakes were $700
if you get new rotors DBA ones are $770 all round
add like 3k for all the little things you forgot about
add a couple of k for more things forgot about lol
Then double it and that will be how much it will cost