Training a 1 year old

Is our 1 year old still a "puppy" for training purposes or are there generally different guidelines or methods we should be following? He was once a pretty relaxed, easy-going puppy, but after a lengthy medical issue and numerous hospital visits and some maturity (I assume), he's gotten a bit more aggressive with barking at people who come over and excited nipping at my kids when playing (not aggressive or mean). I can't stand the barking and need to put an end to it - both when someone comes over and when we have him out on a leash. Would you suggest I follow the same protocols that have been mentioned on the boards for younger pups, or is there a resource that's more specific for 1 year olds?
Thanks!