[Ladylavender]

I think you need to do both: walk him and play with him. Playing with him will use up some energy, but play mostly gets them stimulated because they are re-enacting aggressive tendency in play. But you do want to continue to play because this makes for a happy dog.

Walking is what is going to calm them down more. Walking makes them use all their senses. They are using their muscles, brains, noses, eyes, etc. This is what is going to tire them out and keep them calm. They need to walk every day. But the good news is.... Because they are a small breed, a walk as little as 15-20minutes a day (but i would suggest longer, since you are away all day) is enough.

Now the biting and chewing is another issue that is behavioral in nature. You must begin training him now that this is not ok. You need to stop the behavior just as soon as he does it. It may get to the point where you will have turn your back on him and ignore him, if he just refuses to quit. He needs to understand that the biting behavior gets him no attention. NONE

The chewing, you need to get him plenty of chews, like bully sticks or pig ears and any time he chews on something inappropriate, you need to replace it with a chew toy that is appropriate.

You must be consistent and and firm about what behaviors are acceptable and not acceptable. Your puppy will not learn on his own. They are like babies where they need to be taught everything! Of course how you teach them is different than teaching a human baby and maybe going to puppy classes will help you understand how to go about it.

Good Luck