bump to displacement
 

I don't know much about displacement maps yet but I was wondering, can you create a bump map then use it as a displacement map? This would be cool. You could use the map as a displacement for close-ups then switch it to a bump map for angles that aren't as close to the camera to save render time.

Yes, you can use the same map for either a bump or a displacement. That's a good way to approach it. Avoid the displacement as much as you can.