Live in Staff

I'd say there's no real Standard when it comes to live in staff, You can write this policy yourself as long as it complies with your local law. 

Hayden JD is right.  You are free to set your own terms.  Some of the websites where people look for jobs might impose their own requirements or limitations.  For example, I have heard lately that WorkAway requires you to provide food and won’t let you ask work exchangers to work for more than five hours per day.  They also don’t want you to conduct a Skype interview before your worker arrives to ensure a good fit.  While this seems strange to me, it is their prerogative to enforce any conditions they want.  In your hostel, however, you can decide what you need from workers and what you offer in exchange.  

Some other alternatives include Hostel Jobs, Working Traveller and WorldPackers.

As far as what role they play in your hostel, you have two options:

1) Choose the tasks that you need to have accomplished and look for a work exchange volunteer to do them. – For example, if you need someone to run a pub crawl, then you can look for someone who is socially gifted, entertaining and responsible, and then offer them a position.

2) Find a work exchange volunteer you like and then put them to work doing whichever tasks best fit their skill set.  – For example, if John Doe is a talented artist, then you might assign tasks like painting a mural or decorating your common areas.

I personally love the idea of cherry picking the best and brightest from among your guests and offering them work, because you get to meet them in advance, they already know what kind of atmosphere you’re trying to create, and you can set any conditions that you want as long as they are beneficial for everyone involved.