A camera is what we call "extra low voltage", so the voltages present in camera's are not such that you need worry about human shock hazards nor fire.
You mentioned a camera, then a light fixture....not sure what your putting outside in front of the garage?
- If its a camera, don't worry about it, as said above.
- If its a light, you needn't worry about it neither, but if you want to connect it downstream of a GFCI, you can. It is odd to stuff a GFCI into a closed junction box. Remember that the GFCI has a reset button....to reset it, you'd have to remember its in the box, and thereby open the junction box to manually reset. If you do use a GFCI, use what we call a "dead front GFCI".
14AWG and 15a GFCI is fine....All good.
Good Luck....let me know.