I always put the cooked food on a clean plate when I grill, but do I need three spatulas - one for raw, one for turning the chicken and a third when the chicken is cooked through?
You need one clean plate and one clean spatula (or tongs) for the fully cooked meat. For the stage in between when you are turning partially cooked chicken, you can use the same spatula you used to put the raw food on the grill. That's because the food will continue to be exposed to heat (especially on the surface) for a sufficient amount of time to kill off the bad bugs.
When I grill, I bring one clean platter or plate and a clean spatula outside with me when I bring the uncooked food out. That prevents me from having to run indoors in the midst of grilling and risk overcooking our dinner! For more tips, see Food Safety Tips for Grilling.