Everything is made of “HD” Voxels, aka the resolution of 32x32 Minecraft Texturepacks, so at the very least you are kinda forced to use Cubes and Slopes. And there can always be a different Style Furnace that does the identical Functionality.
Neither in this specific case. ECS is not limited in that way, and the Stats System for Metals could just have new made-up Stats added to Materials, which then could even be automatically be added to procedurally generated Metal Types.
Considering all Races are custom, it would be very shortsighted to give an attribute on a per Race basis. And it would be mandatory to give at least some procedural way to randomly apply the Attribute to all Races, because if you dont, then it will just be added to all generated Races anyways without any discrimination. (you can disable the stat for random races, but you have to actively disable it, you just cant forget about deciding)
This one is a bit complicated, but you might need to consider some of them when making a Mod at the very least. You can however just say “I want the Stove to be available somewhen after Campfires are discovered” and then say that the “Cooking Pot” should be after the Stove, and then just let the Game generate appropriate Science based on that.
Tools will have a very special System to work with. People can customize Shape of Tools for their needs. You can have a Diagonal Handle or a Straight Handle just fine, same for double-diagonal Handles (two opposite points of a Cube). And oops I have read Shovel instead of Stove. I’m gonna put this at the end of my Post then. XD