Phylogenic bracketing makes at very safe to assume that since basal dromaeosaurids such as Microraptor or Sinornthosaurus were feathered, and that more advanced dromaeosaurids like Velociraptor were feathered, there is no reason to assume that Deinonychus wasn't feathered. The pebbled skin, however, is just something I've picked up from multiple sources. I don't know what evidence we have for it.