The levers look and sound pretty the same... as for the cables and housings yes, you can use the cable cutter to cut the housing, but you will need a sharpened spoke, paperclip or something to flair and open the cut end. Also don't forget to get ferrules and cable ends. For housing and cables just go to the LBS... shipping would cost more than that stuff.
I'd not get either of those levers. I know for a fact that eh dia-comp levers are junk, I have them on my fixie. one is a dummy lever now (no lever, just a hood). but they are way less comfortable then the shimano ones. heres the good shimano ones. get either the tiagra or 600...not the dia comps. trust me on this one, man. http://sheldonbrown.com/harris/brakes.html#leversdrop
as for housing, if you look around the sheldon brown site, i'm sure they have it somewhere so you dont have to pay excess shipping.