I do not have suggestions for all your problems . For # 3, you said your pup was 7 months old, and the chewing started a couple of months ago. That sounds like a teething problem to me. I'd give your pup lots of cold stuff to chew on...ice cubes, a knotted facecloth soaked in water and then frozen, carrots, and then of course chew toys like rawhide, but supervise them when they have these!
Now, for the other 2 points, I have met a couple of Pyreneese/Collie crosses, and they were both very shy. One actually would not move in puppy classes for a number of weeks. Whether this is a breed thing, I really would not know for sure.