Shear is when you put a load on something, and how much weight it takes for a rod to bend or break when you put weight on a rod supported on both ends.
Compressive is how much it resists going "squish" under a lot of weight when you load things on top of it when it is supported underneath (or when you crush it between two things)
Tensile strength is how much something will "spring" back into shape after being bent. The difference between tensile strength and shear yield strength is in whether the object "elastically" deforms (goes back to its original shape) or "plastically" deforms (stays bent).
Torsion is if you twist something instead of just bend it.
The difference between yield and fracture is that fracture is the point where the thing just plain fails and snaps or is crushed, while yield is where it is merely deformed. However, as something deforms, the resistance it has to further deformation becomes weaker, and it gets closer to simply breaking entirely.
Molar mass is basically related to density on the molecular level. It is the mass per mole (a specific number of molecules), and so it's a function of the atomic weights of the constituent atoms of the molecules of a material. It's something that all these shear strengths and densities and such derive from in real life, but it's a distant thing in architecture - we only need the derived numbers.
Basically, I think all we really need is shear fracture, with maybe some compressive fracture, but in a way that doesn't become too imposing on the player.
Shear fracture would be checked on how the "ledge" that juts out is supported (or not) when it reaches over. Making an arch, where you have a thicker wall that supports less weight the further away from the load-bearing wall you go, would be a good way to support weights over large distances without supports.
The "chandelier" idea would be handled by this - you just add its weight onto the supporting ceilings for tests of shear forces on how well the ceilings hold up.
Doing this, we wouldn't be testing if the load-bearing walls are going to be crushed at all, just testing if the "ceilings" or "floors" have the structural integrity to not fail as they are extended over unsupported space.
If you absolutely must do load-bearing walls where those walls can crumble under the shear weight of the walls they are supporting above them, then it's a matter of dividing out that mass from above across all supporting tiles below. That's where you get the "cascade" calculations, where stress flows downwards from the top, with each tile adding its own mass onto the stress that flows downward, but where it gets divided out across other stones if there are multiple tiles of support.
Presumably, tiles that have other stone walls beside it should never fail, no matter how much pressure they are under. They might be under enough pressure to deform, but if there's no place to deform to, they just get compressed. This is pretty much the point where you put enough pressure on something to turn sand into sandstone or coal into diamonds or something, but we don't really need to model that.