That is really cool!! Both of your boys are gorgeous but I am not sure who is who, is Linus your black or your yellow?
I wonder why they would want to teach bad habits. I would not want to teach most of those "tricks". I did teach Maxx to "hide his eyes" when he was a puppy. I just placed his paw over his nose, near his eyes, clicked and treated. He also loves to learn and he would probably do almost anything for an apple slice. He also "holds" my hand very gently, in his mouth, when he wants to show me something or take me somewhere. I didn't actually teach that, I think it came from reinforcing "gentle" when he was teething. I think he taught himself that one, lol! It is probably not a very good thing but he only does it with me and as long as there is no biting I am ok with it. (I actually think it is sweet!) The way you describe Linus he sounds very smart and willing to learn, I have a feeling you can teach him just about anything! Have fun and let us know if we might be able to see something he does!