you can use a 7 or an 8 speed shimano index shifter. the cassettes are the same spacing if I remember right. the dedrailer wont care either way. 9 speed and up uses a thinner chain. Although I have heard some people say you can use an 8 speed chain on a 9 speed set up MY one and only attempt to do this resulted in excessive chain noise, rub, and front trimming.
for the front you need to use the derailure designed for the chain width you are running to get the proper amount of trimming etc. with index shifting. If you run a ten speed chain and an 8 speed f.derailure you will ned to move the derailure excesively to get it to shift. but an 8 speed chain and a ten speed derailure will need to be trimmed more frequently or it will rub alot.
I have also heard that a 10 speed chain can get caught in between the front rings of an 8 or 9 speed set up. The rumor is that the middle or small ring of a 10 speed set is offset to be closer to the big ring to keep this from happening.
mix and match to satisfy yourself. just dont expect it to be perfect. you will have to make some allowances