Do the collar and leash--your puppy will be fine. Oscar is almost done with a 10 week beginner obedience (we'll soon be going on to intermediate). He would not have learned the things he learned in a harness. I do still use a harness for walks.
Animal Inn requires the chain collar, but they teach you the right way to use it and that it is ONLY for the times when you are training. These guys have a lot of experience at what they do. I was reluctant at first, but now I completely trust my instructors.
And before anyone gets upset, the training school I go to has AKC judges and has produced several national champions.
I'd just recommend trying it and then deciding.
