He sounds like a normal puppy to me. How old is he?? I am a homeschooling mom, so we are here all day long with our little guy. I've noticed that the couple of times we have had to leave him by himself for long periods of time, that when we got home he was like a mad man, going crazy, growling and carrying on with his toys and sometimes us. He is playing and has all this energy pent up from being by himself all day. It's good to get him out and run him until he's worn out. It's like how kids are... they have to get the wiggles out somehow.
As for being afraid when you go on walks, I'm not sure. I think continuing to walk him is good. He needs to get used to the sights and sound around him so he will be more comfortable with his surroundings.
I hope this helps. Good luck!