Multi-card setups do not benefit iClone.
Workstation cards do not benefit iClone.
Really powerful CPU's do not benefit iClone.
SSD's might help you load stuff faster, but will not really benefit iClone beyond that. They can be nice for faster disk though.
For a good iClone workstation, What you need is a decent CPU. That means an i5 or better. But you should choose a high end i7 if you can afford such.
For top performance, a really high-end Nvidia GTX gaming card. A 980 Ti or Titan X would be your best bet right now. Lots of VRAM is good.
Get as much system RAM as makes you comfortable. It's pretty cheap.
iClone has a DirectX gaming engine, so double-precision workstation cards have no benefit. If your also doing CAD work, then consider it.
You can export some parts of your iClone projects as FBX to use in external rendering engines, but you cannot export everything. Trees cannot be exported. Soft-cloth physics cannot be exported. And probably a few other things as well.