Take them all boozing beforehand... worked for me
The Precision will cover all eventualities, to be honest.
In terms of preparing, it's a real shame they can't share anything - though, if it's early days, they might not have anything to share. You can still practice, mind - pick out a smattering of rock tracks and just jam out some bass lines over the top. It sounds as if that's probably what you'll be doing in the 'audition', working through any tracks they have; or, if they want a cover, you've got some in your pocket you know.