Karma is just... well karma. You usually nuzzle (which gives karma) for when people on the forum do good things/provide ideas/ help you, whatever. And bite does the opposite.
As for the zebras, that was a banner featured in the banner contest that won. Those zebras are from Impressive Title (The game preceding Feral Heart) and they USED to run around, but that was on Impressive Title, not Feral Heart, as hunting hasnt been implemented into Feral Heart just yet, SO... any zebras/other animals other than canines/felines that you find in screenshots are simply meshes. And the meshes are just the structure of the animals... think of it like a statue placed in a map. They dont run around or move, they're just there for role play hunting or to look at.
I hope that answers your questions.