there's a big debate on the spaying / neutering for the health, because some people believe it should be done earlier in life while others believe it should be done later. for that reason, i don't want to start an argument and i'm gonna not get into that (nothing personal, i hope you understand, i'm just not up for that today ha ha) a lot of the problem is over population of the pets though.
YES, you can give too many treats. pig ears, etc, can give your dog a bad tummy ache / diahhrea, etc if they have too many. i saw a show on tv just recently where a dog got into a bag of pig ears and ate 10lbs (extreme i know, but just worth sharing) and it caused an obstruction. if your pup is doing good on weight (not getting too fat or thin) i would leave the food be, and treat every once in a while. some dogs just can't eat enough! since you say you're feeding three times a day, maybe you could try cutting it down to two, and then just making the two meals equal out to the same amount of food as three times. that way it wouldn't be like eating a cereal bar three times a day, but instead eating a good size meal twice.
how old is spazz? with the heal command, it may just take time. i think i remember reading he was a younger puppy. puppies take longer to be able to focus their attention, and concentrate. just like a two year old, there's SO many new things ha ha. one thing though, may be to walk him before you train, that way he doesn't have too much extra energy. i'm sure every body else here will have tons more ideas for you, but keep us posted! your baby is so cute!