I agree with the other suggestions you've gotten...especially the crate! Also, make sure that your puppy has lots of appropriate things to chew on...he's chewing because he's a) teething and b) exploring his environment. Whenever you catch him chewing on inappropriate things, firmly tell him no (not mean, just firm), remove him from the inappropriate thing, and then give him something appropriate to chew on - a nylabone, a tug toy, a stuffed toy, etc.

He won't be upset or confused if you train him to like the crate. I've currently got a 4 month old puppy that loves her crate. I used to foster for a rescue, and crate trained every dog that came in to my house, regardless of their age. The way I like to crate train is to feed the dog their meals in the crate. I start by setting the food bowl just inside the crate door, and let them stand with their head in the crate to eat. Each day, I move it a little farther in until the dog is fully standing inside the crate to eat. Then I start closing the door. At first, it's just setting the door closed but not latching it. Then latch it, but open it as soon as they are done eating. Then, latch it wait a couple minutes after they are done, then open it. When the dog is calmly sitting in their crate after eating, they are fully adjusted to the crate. I also give them a very special treat when ever I put them in the crate when I leave...usually a Kong stuffed with treats and frozen or some tiny treats scattered in the crate or something to keep them occupied. I make it exciting to go in the kennel, usually saying, in an excited voice, "let's go kennel! Oh boy, here's your treat, where's your kennel! Let's get in and get the treat!"

They come in all sizes, from itty bitty to great big. For an adult black lab, you'll probably want a 36" long crate. If he's still rather small, you can get a wire crate with a divider panel to make the crate smaller until he grows some more. You want your puppy to have enough room to stand up, lay down, turn around, but not so much room that he can potty in one end of the crate and sleep in the other. Crates come in wire, plastic, and even fabric. For a puppy, you'll probably want either wire or plastic. I like the plastic ones, because if a puppy does have a mess in there, it's contained to the crate and you can just take the crate outside and hose it off.

Puppies are so much fun, but a lot of work! My 4 month old puppy is currently asleep in her crate after a very exhausting day.