the link to the springs is here:
http://www.oople.com/forums/showthread.php?t=51315
Personally i've got 2 springs either side of the kit standards so i have some choice.
With regard to spares, get a spare front shock tower or two and the usuals like hubs and which bones etc.
I just got hold of the aluminium rear hangers (LAW36 and LAW37) and they seem to be readiy available and in stock(jespares have them right now)
hope that helps.