Hi @justabouthomes_com,
it's like @james says. The lightbaking is set up to deliver a uniform texel density related to the surface area of the objects. This means 1 sqm of wall gets the same amount of texture pixels as 1 sqm of furniture. This works great if you look at each object in your scene from the same distance but in this scene I assume that's not the case. You probably want to zoom into the furniture. If you want sharper textures you need to increase the density in the sketchfab script. This will increase your rendertimes. If you only focusing on the room with the furniture I urge you to slice off the parts of the floorplan which isn't of interest.
You can also play with the render settings. Not all graininess is caused by texture resolution!
All textures are baked to the diffuse channel of the materials. There's no bump in sketchfab anymore after baking. I'm not sure, but I guess you could exaggerate the bump prior to baking and see what happens. What you do need to do is set up your own lighting though. Perhaps you use the lighting preset from the script. This is a smooth and omnidirectional lighting. No bump is going to show up in that light! you need a strong directional light for that.
Finally, I'd disable the shadows on the lights in sketchfab and set the shading mode to "shadeless". Only then you're ably to evaluate the baked textures properly.
