Puppy Training, biting, aggression? Or being a puppy?

Question
We bought, from a reputable breeder, an 8 week old half Wheaten Terrier and half Cavalier St Charles. He has been well-behaved, has trained fairly easily and has seemed receptive to everything.  We started immediately with house, leash, obedience training and he seems to acknowledge me as "alpha" (won't go through door before us, sleeps in crate on floor with no qualms, will allow handling of his ears, paws..,).  He is now 16 weeks old and seems to be becoming more aggressive/assertive especially when he becomes excited.  He does not like to go for walks (done 3x per day, by me not for potty just exercise but he always starts bouncing and running away when you get his leash, starts nipping when putting it on and if you ignore him or stop he is happy to run back and forth & not walk). On leash, he pulls forward but I constantly stop him and try to get in front.  He heels well when a car or person/dogpasses but close to the end of his walk he starts turning around while on leash grabbing my shoelaces, pants, leash, jumping... At home, he was quite docile now, he is still good but when he gets excited he starts jumping and biting especially my kids.  I have tried loud noises, bitter spray, water spray to the face, time out, yelping, turning around (he just comes around in front of you).  I put the kids behind me and tell him "no bite" but he just keeps biting and jumping.  He is NEVER threatening but does not back down to disapproval anymore.

All of the items and advice I find don't seem suitable because I know he has never been mistreated, I know he gets a lot of exercise & attention during the day, he fears NOTHING like loud noises or pushing your hand further into his mouth when he mouths us, he doesn't mind not going for his walks.  I know he is playng but I want to stop any behaviors early on that could lead to big problems.  He has also started barking when he wants attention or when being reprimanded which he never did before.  On his walks, he is well behaved around people who stop to pet him, he has "play dates" with other dogs where he does beautifully and LOVES (the older dogs seem to reprimand him when he gets too excited and he backs down and sits and wags his tail until re-invited to play or rolls over on his back).  I am over worrying and he will just outgrow this phase?

Answer
Lisa,
Welcome to the world of terriers!  Everything you see is the Wheaten side.

He also sounds like he is not getting enough exercise.  Terriers have tremendous stamina and need hours of exercise. However, ball playing in and outside the house constitute exercise.

Get him a toy where he has to figure out how to get the food out.

And now the nipping,  You have to get control of this and since you have tried all the nice ways of doing this you will have to go to plan B

I would suggest putting a pinch collar on him.  It represents the mother's correction, which you also see from the adult dogs that reprimand him.  You never jerk it, but hold steady and let him correct himself.  In the beginning, you will have to give a little flexibility when he pulls so the correction isn't too harsh, but after that, he will learn what he can and cant do.    When he starts jumping and nipping step on the leash and the collar will automatically correct him.  With that correction you are to say very sternly  NO BITE!! as you have been, but look him right in the eye until he looks away.  You may have to actually get in a struggle a bit with him, (Good thing he is only 4 months) so he looks at you and then looks away.  He has to know you really are angry at this particular behavior.  I would then put him in his crate for awhile.  Use a mad voice and a mad look.  They know a mad look, I even raise my lip at them so I am talking their language.

Keep this going until you see him calm down.  He is going through a puppy stage, However,,if not corrected on the nipping now, he might continue that bad habit and with bigger teeth it could be a problem.

As a trainer, I have used many different methods to correct playful nipping, and I have found with most terriers I almost always end up using this method.  They are the best dogs in the world and their focus is tremendous.  They are bred to ignore pain, so you really have to make sure you have their full attention.
Once he learns when you are really mad, you wont have to do anything but give an "aaah" and look mad.

So good luck and follow through.   By the way, there is no dog out their more loyal than a terrier, not even Lassie.
nancy