Car wax helps preserve the finish and protect from UV rays. When waxing a car should you also apply a layer of wax on head lights to protect it. I assume it will protect the head light from UV and thus keep it from yellowing? Does this seem correct..if I apply wax on the headlight, it will retain it'* new clear appearance longer?

What wax or Uv product are you currently using to protect the lenses? Wax should be fine.
As your vehicle is less than 7 years old, they are probably in good clear condition already.
For my old 97 Park Ave, I have used Mother'* 08808 Power Plastic 4 lights. Sure keeps them clear.

The wax I have been using is ArmorAll Ultra shine (Butter smooth wax) fortified with carnuba . It doesn't specifically say that it protects against UV rays.
When I replace this, should I look for one that says that it has UV protection or carnuba does protect against UV