I am about to go into production on a short for festival submission. I have someone interested in taking production stills with an SLR that will become part of what I submit. In the past I just took a few quick digital shots--which I realize was not really up to par. So my question is what should I have them shoot for me that would be of most use for festivals. Color or black and white? Slides or prints? They are not really a digicam person so I will probably get some digital snaps as well seperately.

If you shoot on film you can scan those in and most photolabs
support getting you the stills directly on CD as well.

Photo taking is just (perhaps more) a difficult skill as video work,
so someone dedicated to taking just stills and knows what he or
she is doing is going to be a great help.

Ofcourse a simple digicam will not produce the shots you are
looking for. So I'd go with a high quality digital camera or an
"analog" one.

How the stills should look would largely depend on your film and
style you want to convey I'd say.

Keep in mind that you can post-process still photos as well to give
them the atmosphere you are looking for etc.