Here is what I need to do: Spawn Mobs with a custom name and Armor. Said armor should have lore that says +50 hp Mob do not have normal health, but have health defined by their armor. Mobs drop said armor or their weapon(which also does damage based on lore) to the player occasionally on death. Player does not have vanilla health but has health defined by armor. Each player has their health displayed by a wither boss that only they can see. Taking damage lowers an integer that represents the player or mob's health. I am trying to make a plugin like this.
I simple search on google has the answer for your first question right at the top! https://bukkit.org/threads/create-and-spawn-custom-entity.269913/ You can search the rest on your own.