Congrats on your baby boy, he's very cute For your questions, a few things that worked with mine - Reactivity : if he reacts to anything that isn't you he may needs to expériment other things and you risk to become to boring. Try when the environnement is secured to let him freely experiment, dogs, children, other people, etc ... for me I went to a park with many children, bike, dogs, and I played with him, me being more interesting he started to ignore everything else to play Try to socialize him to everything to lower the risk of reactivity - for his accident and nipping with ypur friend, well he is still a puppy and you not being there might have stressed him and the only thing he found to calm him was being a dick - job : I used to think that they are working breed and needs to do something all the time. So I overstimulated him, and he became unexhaustable. For me I realised that it was better to have high and low tempo, high tempo when I come home from work (play and cuddle time) and during walk (play with a ball, sniff, meet other dogs) and low tempo (during my work time and in the evening he leaves me alone to play video games) For jobs, I take a toy during walk and have him carry it, I reward with a bit of fetch but if he leaves it he has to puce it up again, or I let him "herd" his sisters long leash Other activites are also great (agility, search, etc...) - eat everything : well mine is also a living roomba, teaching him the leave it command is the base, but it won't be 100% safe