Well, most writers do break up dialogue with “he said” and “she said.” It’s one of the best ways to get the right pacing. What annoys me is always finding “he said” and “she said” at the beginning or end of sentenecs. Read good writers, and you’ll find a LOT of dialogue broken with these attributions.
This sentence: Lizzie laughed. He owns a condo down there, she said. Try competing with that. doesn’t need “she said” at all. Placing “Lizzie laughed” on the same line is already giving attribution.
As for “since,” since you asked, it can be used to indicate time, but it’s also an acceptable substitute for “because” in casual writing and dialogue, and pretty much all fiction is casual writing.
As for the five senses, use all five, but not all at once, and don’t go overboard with any of them. Sight should be used most often, touch and taste the least often. And none should be used except when there’s something relating to one of the senses that the POV character would notice.