I have a Black Lab/ Pitt mix as well. Everything I have read above thus far has been pretty close to my experience. Reece in fact is incredibly smart and is always trying to please me; he learns tricks quicker than any other dog I’ve had growing up as well. He has never shown any aggression toward any other animal even cats (although squirrels intrigue him because of how fast they move). He loves all humans, especially children but can play rougher with them than he will with adult females. He does seem to be intimidated by the smaller dog breeds that yip at him. He is submissive toward dominate female dogs vs. males so far, until they give him the OK that he is friend material. The chewing EVERYTHING is what I can relate most too. We have given Reece his own toy box to choose from, we always have to lock up our trash, and he is blocked off from many areas of the house. He is afraid of water, yes even rain so we are unable to enjoy him at the lake or convince him to use the bathroom during the slightest sprinkle. I have never experienced the food aggression that others report – as I can even take a bone from him while he is chewing to move him out of the way of company – I warn him though first.
The most important thing I learned is that Reece is so high energy that he needs to be exercised when I get home from work before I can relax or there will be no relaxing at all. After all, he has missed me all day long and has no idea how good or bad my work day was – he just wants to play with me and show me how much he loves me! Congrats on your new baby – I for one have never been happier!

Not sure if this will help but I was Reece’s 3rd and final family as well and he was 4 months when we got him. I found that no amount of walking would stop the accidents and soon discovered that Reece associated walking with play time. As soon as I started leasing him in the backyard he began to change his behavior and learned that outside was potty time. It’s quite possible your pup doesn’t realize that walking = potty time. Good luck!

Reece has the same problem but really only does it with my teen-aged son and his friends, I really think he senses that they are built for rough play. But my son has gotten frustrated that Reece won’t ever just cuddle and be gentle with him. So we have resorted to time outs on his puppy bed and because it’s not a crate and he can attempt to leave time out we can continue to redirect him back to the time out and he is starting to get the concept because of the consistency.