There is no need to discourage it. It is a phase and will pass. He just figured out he can make this really cool sound. When the novelty wears off he'll stop.
As for biting, I calmly said, "no biting" and if she repeated, put her down. I'd pick her right back up if she wanted but if she repeated the biting, I repeated the putting down. She got the message very quickly. Your son finds your reaction really interesting, which is why he is laughing. This can prolong the behavior, which is why I went with the no reaction method. No, he won't be a psycho. Totally normal!! :)
One thing I did find helpful was sign language. A lot of kids, it seems, when they cannot communicate in the second year do a lot of high pitched screaming in an effort to talk. DD never did that because usually she could get her needs across to us. She did still enter other phases of new and louder noises, but they also passed since we didn't make a big issue of them.
Discipline is actually teaching, it doesn't mean punishment. You have a while yet before punishment will be an effective way of curbing his undesirable behaviors. There are also non-punitive methods of discipline that are effective. I'd definitely avoid getting his attention by flicking him or misting him. That might be good for animal training. But really you don't want a 6 year old who think it makes sense to flick his classmates to get their attention when they are doing something undesirable to him. They learn by our actions.
A book I thought helpful in understanding my toddler was Karp's "Happiest Toddler on the Block."