You could use either or, theres no set rules, just what you feel more comfortable with, check out the fire ring tutorial, that might give you some ideas.
As for using a plane and a photo, that would do the job for the "static" sand, if you know what I mean, also if you want to start making footprints then your going to be looking into softbodies (theres a free tutorial at digital tutors in this)
"No pressure, no diamonds" Thomas Carlyle