The bridge is small, Isn't it? I always wondered why, at the very least, they did not go with the extra deck (5) as used by Hiryu. I find it hard to believe that top weight was that much of a concern for an extra island deck. Probably more of a concern with reducing flight deck obstructions. That priority obviously changed with all the designs that followed.
To respond to your 3 questions:
1) Open, though I've always thought an oversized hatchway a possibility. See first pic of Zuikau 1942, credit Gakken #13
2) As the photo illustrates, the bulkworks are straight upright, excepting the front of the bridge.
3) The balcony is there, as it is on Soryu and Hiryu, though it is not a balcony. I believe it is a form of wind baffle. See 2nd photo form the Gakken Deluxe volume on Zuikaku. This is Zuikaku's bridge front, circa 1943. I think that's the captain posing in fornt of the bridge. What cannot be seen is the upper protion of the bridge fron with a proper set of wind baffles. You can see the side of them in the first pic. Also in the 3rd pic of Zuikaku's island 1943, though not very clearly. Credit Maru Special #102. More clearly seen in pic #4, the cover of the Gakken Deluxe volume on Zuikaku
Attachments: |

Zuikaku 1942 bridge, Gakken #13.jpg [ 119.14 KiB | Viewed 14349 times ]
|

Zuikaku 1942 Bridge Base & Director, cropped.jpg [ 80.24 KiB | Viewed 14342 times ]
|

Zuikaku island, 5-27-1943, MS#102 p12 small.jpg [ 114.4 KiB | Viewed 14342 times ]
|

Zuikaku 1-100 Model#1 small.jpg [ 135.77 KiB | Viewed 14353 times ]
|
|