Question: What are some grilling tools that a beginner should have when purchasing a new grill? Additionally, are there tools that are useful for the more advanced outdoor cook?

Answer: 
In addition to what others have said, you should have TWO of each meat-handling tool (tongs, mainly). That way you can use one to handle raw meat, and one to remove cooked meat.
If you're using charcoal, a spray bottle with H2O can be handy for flare-ups. Otherwise, I think others have the bases covered.