ANSWER: Gloves are very handy for when working with strong dogs that have a tendency to pull on the leash, with dogs that have a tendency to bolt, and with aggressive dogs. In general, gloves protect your hands and give you extra strength during the training process. They also keep your hands clean and warm when having to handle the training line in wet, muddy, and/or cold conditions.
Regarding the collar size, ideally you should begin training the day your puppy comes home, so you will need a small Command Collar for sure. It depends on your efforts and how quickly your dog responds to the training (depending on his personality and strength of will) as to whether you will need to continue training into the stages where your dog grows bigger and will be in need of a large Command Collar. Some puppies can be fully trained within a matter of a few weeks.