It's a bit complicated. But as far as I know, 1:100 scale is what Unity recommends, as its physics, default camera settings and default Sprite settings suggest. They also say so in their official videos.
To be honest, I don't like dealing with 0.01 numbers either. 1 unit : 1 pixel scale has numbers much cleaner to look at and doesn't cause weird floating point values in the Inspector.
But Unity has a lot of other things that causes it to act weird at 1:1. The physics system (both 2D and 3D) velocities cap out at I think around 100 or 300 per second. Which is just absolutely too slow for the kinds of games I like. 😃 And I think the reason why shadows don't work is because of LOD/shadow resolution caps.
That's why in the end, we just decided to go with the 0.01 scale anyway. Just don't forget that 1 Unity unit = 100 sprite pixels.
Are there other shaders that can cast shadows with point lights in Unity?
(btw, no I haven't gotten normal maps working. But I wasn't really trying it out at all anyway. I do hope to use it sometime though.)