What is Casper’s approach to slashing? Will it be a flat percentage?
We are still conducting research in this area. With PoS networks, network security really correlates directly with in-protocol slashing for equivocation. At the same time, we are aware that this is new software, with a non-zero chance of bugs occurring. 
We may consider a flat percentage, or an increasing percentage with each subsequent fault. We will present our approach to slashing during our community calls and publicly in blog posts.