Is it good Feng Shui to add a door and multiple storage rooms in the kitchen? Is it okay if the storage room door faces the balcony door?

As long as the door added in the kitchen does not face the kitchen door, it will be fine. The door facing the balcony is not a big problem. Pay attention to moisture and fire prevention.

If you are really worried about the door-to-door problem, you can design the flat door as a sliding door, make it hidden, and add some patterns on it, so that even if it is relatively small, it will not be a big problem!

Good luck!