dont't worry about it. Its normal! My son experienced exactly the same thing when he was 3 weeks old. I was also thinking the same as you that he has some phlegm in the throat. He used to breathe awkwardly as well. Different sounds used to come always but it feels they have phlegm although I dont't think so they have.
I asked to a nurse and she said its normal. And after few months it went away on its own. And about the sleep, they will find it difficult to sleep that time...I had to put so much effort to put my son to sleep when he was 3 weeks also. So dont't worry about it Mummy!