Help making datapacks for a modded server.

This is going to be a long explanation, so buckle up. You see, not too long ago I've made a Forge Minecraft server that is EXTREMELY unbalanced. Normally, I would be ok with something like this, but after playing in my own server with other people for a few days, I realized that you can beat the game extremely fast with some OP gear and tools. Because of this, I want to restart the server with some datapacks to balance it out more. So what exactly am I looking help with? Basically everything. I've followed guides from wikis, I've looked at YouTube videos explaining how to make datapacks (vanilla or modded), and I've even asked for help in other servers, but to no avail. As for what kinds of datapacks I'm making:
-A datapack to change the recipes of certain items so they are harder to get (to the point of being end game).
-A datapack to change the loot table of both mobs (add or remove items that they drop) AND chests (blacklist certain items from being obtained in chests, but can still be crafted like normal).
-A datapack that blacklists items from being obtained in any way (specifically creative mode only items).
-A datapack to blacklist items from a mod called Randomium.
There might be some other stuff that I need help with, and I apologize if this is alot to take in, but its something that im willing to learn and to make it work in my server. If you have any other questions regarding the modpack or something else, be sure to ask me. One more thing that I want to mention is that I'm also using utility mods to help me with this, specifically Item Obliterator and CraftTweaker.