How can I create/add custom behaviors, animations and abilities to custom or existing mobs?

Hello,

I'm would like to try some very specific things and put some ideas into the game, but I don't know how and if the will work so...here I am.

1) I wanted to try to make a fish that would glow in the dark. But not glow like a Glow Squid or Enderman eyes which the glow is only applied to the texture, per say. I wanted the fish to glow like a Sea Lantern or a Glowstone. I haven't read everything yet about light in Minecraft, but I'm reading this wiki page to understand how it works: https://minecraft.fandom.com/wiki/Light .

2) I would like to make an item called Glow Stick, which could be crafted with the drop of the glowing fish. Can I apply a glow to an item that works like a torch, but I could hold the item and it would glow on the player's hand?

3) I recently could finally put my first custom mob inside the game (after A LOT of headache), the Ambylotl. The idea for it is that the Ambylotl to be a kind of a hybrid between Wolfes, Dogs and Axolotls. It would follow you after tamed with a bucket of Cod (but you could make it sit), it is a neutral creature (so if you hit it, it will hit back), it attacks aggressive water mobs by default (such as Drowned and Guardians), it has a custom swimming animation and when it comes out of the water, it would shake just like a Wolf/Dog. Some of these behaviors I'm trying to add via the AI function that MCreator offers. But how do I add: the attack aggressive water mobs by default behavior, make it sit when I right click on it, the swimming animation and the shake animation? Also, when I try to breed it, it didn't breed and make an baby. Is it because i forgot to mark something on MCreator while making it or is it a bug? Also, (I'm gonna test this on Survival Mode) it didn't attack mobs that I hit after tamed.

4) Ok, let's start with the tricky ones. I would like to make a cow, Moobloom, which by default looks like regular Moobloom. But you could feed it flowers and Sweet Berries and it would change it's appearance based on the plant you feed it. For example, if you feed it a Poppy it would turn red and Poppys would start growing on it's back. You could use a Shear on it and the Poppys would grow again! Bees would interact with Moobloom if the Moobloom has flowers on it, by pollinating the flowers.

5) I would like to make a neutral creature that is a grey, traveler Enderman. It would function exactly like a Wandering Traveller, but instead of Emeralds, you would exchange blocks with it and it would keep wandering around instead of staying in the same place (it can teleport and doesn't like water to).

6) I don't know if I'm gonna really make this one, but since I'm already here I want to ask about it because understanding it's mechanics can help me in the future. I think I would like to make a sort of corrupted Enderman, which would spawn on the Nether and a uncommon/rare "End Fortress" like custom structure. The concept is that is is a much powerful version of the Enderman and it goes to the Nether to collect a certain type of custom/modded block to help build "End Fortresses". It would behave just like a regular Enderman, you stare at it to much and it attacks, it can take blocks, use pumpkins so you and stare it as much as you want; the only differences would be It can come out from the Nether portal sometimes, like the zombie pigman did, and the sounds I guess. Also, because of them, there would be a few very, very, VERY special and rare portals to the End on the Nether dimension. Oh, by the way, how do I make it come out of the Nether Portal as mentioned?

7) And finally, last but not least, I wanted to make a creature that the player could make....kind like the Iron Golem. For now, I picture it like a enchanted jack-o-lantern pumpkin with wings, that follows the player, illuminates its surroundings and shoots fireballs on mobs that attack the player. You would spawn it by using a special enchantment and making a sort of ritual with a pumpkin that is still on it's stalk. You could also craft a whistle so that, when you blow it, it stops following you and just flies around, but it doesn't despawn (although if you make that happen in a open space, it could sort of run away  from you, so you would need to attach a Lead to it or just let it go inside a closed building or something). It's a passive mob that would defend you, and you could heal it with a compost (or something like that). Soooo...is it possible to make such a mob? How do I make it?

Thank you if you made it until here. I will be very gratefull if someone helps me. And I'm planning to try to make some tutorial on how I created and putted Ambylotl insede Minecraft. Thanks for your attention.