Is it healthy to feed a hamster one piece of non-sugary cereal often as a treat?

definitely!!! a non-sugary cereal is a great treat for the little hamster!!, IF you give it to him no more then twice a week. also to the second question you ask i say YES. they love to get outside!!! i put my hamster in the grass outside about once a week and she loves it! i think she even gets sad when it is time to put her back in the cage again. as long as there are no dangers like dogs and other stuff it is ok. oh, but can i tell you something? my hamster and my dog are like almost friends it is so weired! so i never worry about my dog eating it. and NO to anyone who thinks i am trolling about my hamster and my dog, it is true!