First of all, I think, fast and powerful CPU with 4 cores is needed, because the renderer in IC is now using multi-thread.
The amount of RAM is never be very much. You can use as much as you can get.
The graphic card in this case not very useful. Until, the renderer can't use GPU.
And finally, you can use the TeamViewer to rule by the RenderFarm.
PS: Tom, what kind of images are you doing? Can you show some samples? Very interesting to see.