How do I use the stealth belt to listen in to the conversations of Vogg's guards, so i learn about how the Kath Hounds are put to sleep by Juma Juice? Or is there a way to skip this and get straight into Vogga's secret vault?

You can't skip it. You have to use the stealth belt, sneak into their room in the docks, then listen before going to the bartender.

Use the stealth belt by equipping it to a character with levels in stealth, and then click on the icon for stealth in the lower right menu. =)

i got the juice but it i know i need to distract vogga by dancing how do i do this bit?

If you have a female lead, she can do it, or the handmaiden can. Just equip 'em with the suit, and they will dance for Vogga. He will fall asleep and you can slip the juice. =)