No way. 30mm HE sure is quite powerfull against thin skinned aircraft, but it utterly useless against 60-100mm armour.
Crew, unarmored guns, various stuff at fly deck, mb fly deck itself can be affected, but not a hull.
Not directly, but get enough fires going and the ship is either dead or a floating scrap heap. IIRC none of the bombs that killed the Japanese CVs at Midway penetrated past the hangar deck; the ships were turned into blazing hulks from the fires started among the planes, ordnance, and fueling equipment on the flight and hangar decks, and were either sunk by their own magazines exploding or scuttled with friendly torpedoes. U.S.S. Franklin took similar damage in 1945 and, while skilled damage control barely enabled her to stay afloat, she took months to repair and was out of action for the rest of the war.
AFAIK the question of whether strafing a CV with armed and fueled planes on the flight deck could produce similar results was never put to the test, but it doesn't strike me as out of the realm of possibility - especially if you include the possibility of some rounds getting through to the hangar deck, given that none of the US CVs or, with one exception, the Japanese CVs that saw significant action had armored flight decks or hulls armored up to the level of the hangar decks.
