This is a known OptiFine bug. Turning off Dynamic Lightning should fix the issue. Please note that the Bug Tracker is only for Vanilla Minecraft bugs, not third-party ones.
I assume you have already checked your texture packs?
If you hear a zombie growl, there is definitely a zombie nearby, whether it's in a cave or somewhere you haven't checked yet. In a test world, you can use the following command to teleport all zombies within the bed radius to you, to confirm their presence.
/tp @e[type=minecraft:zombie,distance=..10] ~ ~ ~
This is very likely a client-side bug/issue. If a torch was dropped, then the pickaxe is probably still in your hotbar, you just don’t see it. Clicking the hotbar slot in your inventory makes the pickaxe reappear.
This isn’t a bug, please don’t use the Bug Tracker for support requests. You can find help here: https://answers.microsoft.com/en-us/xbox/forum/all/minecraft-multiplayer-is-disabled-please-check/0866ae8b-a16f-4a55-993a-2ece21d9146f
This is intentional. The happy ghast was added after the spawn egg textures got updated, so there is no old texture of it, only the new one.
This bug isn't related to Minecraft, it should be reported to OptiFine instead. OptiFine makes a lot of changes in the background, particularly with regard to colormaps.
This is intentional. You can feed Ghastlings by right-clicking on them with a snowball. They don't eat snow golems.
This is intentional. Just like grass and other foliage, leaf litter has the replaceable tag, meaning it can be replaced by blocks, which is useful for building.
I think this behaviour is intentional. It controls the ticking flow, which also includes the playtime statistic. The tick command is an administrative and debugging tool, not something that was created for casual players. It would also be strange if the playtime statistic increased when the game was frozen.
I can't confirm this, but if you could provide more information on how to reproduce the bug, that would be great!
I think this is a bug, or at least something that should be changed, as allow-flight is set to true by default. The Happy Ghast allows you to fly on an entity, it's a game mechanic and shouldn't be disabled by a setting that's there to kick players who move incorrectly.
Can confirm
Can confirm, this is particularly noticeable when you can't see the face because it's against the bone block.
This is probably intentional, as it's the perfect distance at the moment to prevent the player from standing inside the happy ghast when it grows up.
Can confirm
Can confirm, the different textures don't work at all, not just in the creative inventory.
Can confirm
Can confirm
This is a known OptiFine bug. Turning off Dynamic Lightning should fix the issue. Please note that the Bug Tracker is only for Vanilla Minecraft bugs, not third-party ones.