Around the outside of the garden you can spray Bonide Repels-All. It has a smell that they won’t like but that you won’t notice. I CANNOT be sprayed in the Vegetable Garden on food crops though, only around the perimeter. Inside the vegetable garden you can spray Hot Pepper Wax spray directly onto the plants and the chipmunks won’t bother them.
To get grass instead of moss, there is no quick fix. It will require removing the moss, correcting the pH of the soil and reseeding with the appropriate grass seed blend…more on that HERE.