Thanks for the insight about hyphens, Joe. 
Sometimes I just think it's awkward to start a new sentence though. I could think of do I really need the information I'm putting in this hyphen or paranthesis? That would reduce my usage of them, but sometimes I feel that the information actually is important to the story...
What do you think of this usage of a hyphen, the kind that bothers me when I write it but I can't stop? (This is from my NaNo story.) "Not only had his savior turned out to be a girl, but she was young- she couldn't have been more than Jack's age." Or the other usage of hyphens that I was talking about previously (from something else I wrote)- "I fall asleep to nothing- no music, no roommate chatter- and my sleep is equally undisturbed."
I'd consider re-writing those sentences in this manner:
1. It was almost beyond his capacity to accept it as fact, but his savior was a girl who could not have been older than Jack himself.
2A. I fall asleep to the tranquility of a peaceful room which cradles me until I awake.
2B. With neither music nor chatter from my roommate to disturb me during the night, my sleep was undisturbed.
My issue with your second sentence is that the overwhelming majority of your readers understand what the word "nothing" means. It serves no purpose to give examples of what noises weren't there when you've already let them know that there were none. All it does is pad your word count. An editor would cut it in a heart beat. I would use something like 2A to replace your original sentence.
Unless...
There was some reason why the absence of music and chatter was especially important and/or unusual and needed to be noted, in which case I would go with something along the lines of 2B which addresses that point directly while keeping your sentence flowing.
Remember, I never said that the information following the hyphen was not important. If it needs to be there, put it in there. Important information, as a rule, can stand as a sentence on its own. It's up to you to construct that sentence in a manner which complements the surrounding sentences.
