Getting an AuPair

I'm after anyone's experiences/advice with getting & having an Au Pair?

I live in Cairns and have 2 kids (8&5).

Can anyone tell me what their experience was with them?
Are you glad you did or did you regret it?
Which agency or how did you go about getting one?
Are you able to set the rules, in terms of them not bringing boys home etc? (I wouldn't feel comfortable with that, with my kids around)
Is their times/hours flexible or do you have to give them a set amount of hours/roster?

Sorry if this sounds like a silly question. I've heard of people that have them but am a bit nervous about embarking on the journey myself.

Would welcome all feedback...
Thanks heaps!! :)