This passage is from The Children's Bach by Helen Garner
They stopped at the gate lounge. The door opened.
‘Here she comes,’ said Elizabeth.
‘Which one is she?’ said Dexter.
The man walking behind Vicki was talking to his friend, he had a faint stammer, not much more than a hesitation. ‘ ’Mazing guy, Gaz. Always thinking about his mem, mem, member. There was something in his brain that just went sprong. He’d see a good looking chick dancing in front of the stage, he’d go down between sets and find her, and he’d be back five minutes later doing up his fly.’
His story was bodyless. A mosquito might have been whining it next to her ear. The footsteps of the hastening passengers beat light and fast. Either the windows were tinted or Melbourne was already dark.
Does "he’d go down between sets and find her" mean "he’d go down between stages and find her"? Dose "set" mean "stage"?
And about the phrases "Mazing guy, Gaz" and "There was something in his brain that just went sprong" Does he speak like that because of his stammer and he wanted to say "Amazing" not "mazing" and "sprung" not "sprong" and Does "There was something in his brain that just went sprong" mean "There was something that suddenly came to his mind"
Does "A mosquito might have been whining it next to her ear." mean "The man's speaking to girl's ear was like whining of a mosquito"?