Yup that sounds like a puppy. Punishment shouldnt really be something when it comes to training. It should be more fun based, I also think you would be hard pressed to find a pup that would listen to most commands without a treat or reward in your hand at that age. The key thing here is that you need to be consistant with all of your training, especially the potty training. I would look into a trainer if you havent already.
As for training other things like sit and such. I personally like to train with a leash on. That way for me if they dont perform the command or do something else like lay down when i gave the sit command. I use the leash and kind of walk in circles and basically reset the pup/dog and then give another command. Thats personally what I like to do but, people with more experience and or a trainer could probably help better.