how to add a stroke without carving into the letters?

Note the difference between adding appearances to type when selected with the type tool (one stroke and one fill, in that order):

and appearances when selected as an object (any number of strokes, fills, effects, any order):

You may need to remove a stroke added at the type level to get what you want before adding one at the object level.

Krista,

You can just create the Stroke behind the Fill, and set the Stroke Weight to twice the desired visual value.