Charlie, many horses love to explore and play by placing things in their mouths. Let’s first address her placing her mouth on you. One easy technique to modify this behavior is to walk away each time she places her mouth on you. Be sure to never give her something that feels good (be it attention, food or a scratch) right after she places her mouth on you, as she will quickly learn that the bad behavior achieves a desired response from you.
We can also decrease the behavior by satisfying her need to chew and play. There are some great horse toys available for mouthy horses like her, and you can also be creative by providing things like ice blocks with treats frozen inside; a natural-bristle broom head attached to a wall surface; large, solid, food-grade plastic balls to mouth and kick, etc.