A bit lengthy but coding questions for a very new coder

So far I've only properly understood very basic coding when I have an example. For example in Mcreator when making a custom recipe using the recipe element and then opening the code after I could see how it worked/if I wanted to swap blocks/items out with others I could do it via code instead of going back into the recipe element.

I've tried to look online for tutorials and guides but most are either outdated or more advanced and it quickly gets overwhelming for me lol. I've currently got a list of things I want to/need to figure out how to code, which would be a lot easier with examples that would mostly just be replacing items/blocks/code but mostly being the same thing. I can then dumb it down for myself if needed and save it in wording I understand better than all the technical terms.

1) How to animate custom models

I want my mobs to move more smoothly/at different speeds. All I know is that it can be coded in but I have no idea how to do it, if I need to do specific things in Blockbench, even just a simple thing like a fish moving it's fins and tail in a smooth looping motion would be a good enough example which I could then use as a template for the rest/future mobs.

2) How to specify what mob type I am targeting. Such as Villager jobs, White Fox, each individual tropical fish and so on.

For example I want to be able to identify if a Farmer Villager is the specific entity being checked for a procedure. Any specific tag would work because I assume then I could just copy the code and swap that entity with another entity and it would work?

3) How to edit the contents of a GUI/Block

For example I want to be able to have it so when a block is broken an item is spawned in a specific gui/block. A farmer villager getting close to a melon, that triggering a procedure to destroy the melon and spawn a melon in the "Farmer's Chest" ( a custom block with a gui )

4) How to edit the damage/fire rate of custom range items

For example I have custom slime mobs, they shoot new items, coloured slimeballs, but they do the default damage and I would want to be able to increase and decrease that damage amount/fire rate
 

5) How to code in larger structures that spawn flat on the ground

For example I have bear caves, but they sometimes spawn on uneven surfaces so part of it floats/is above water/ has sudden edges ( like 6 tall dirt walls around the edge since it should be in the ground but it spawns higher because it chose say a block of grass that is higher than the rest nearby ) To avoid them getting cut in half I limited it to 1 chunk so also how would I go about coding it to avoid dodgy chunk generation

Any examples/very new coder friendly advice would be appreciated.