I think there is a huge difference between cedar shavings and a cedar board. We ran out of the wood we were using on our coop and ended up using a couple pieces of old cedar board in the run.
RE: Chocolate in dogs. It just depends on the acutal concentration of chocolate. Many years ago, we had a dachshund ~11 lbs. He got on top of the kitchen table and ate 2/3rds of a package of semi-sweet baking chocolate chips. I will spare you the description of the mess we came home to..... the smell of said mess defies description. We rushed him to the emergency vet and after emetics (to make him vomit), activated charcoal, and several days of fluids, we realized he would survive. It was a very close call. However, he did not learn his lesson. A couple of years later, the same little monster at 1/2 a bag of bubble gum. Bubble gum looks the same coming out as it did going in.... very pink! It didn't make him sick, but the image of my dog trying to get the sticky mass of pink gum off his bum is forever burned in my brain.