It seems like you might be moving a file between OSX and Windows, while the shader only has support for one of them. Make sure the shader has Metal and one of the DX ones in the shader settings, so that it compiles to compatible platforms

I'm not sure what you mean - as far as I know, UV channels are separate from tangents and bitangents. UVs are commonly used when generating tangents on import/export, and bitangents are derivative of that and the normals. They're still on a per-vertex basis in the mesh data, not per-channel

Glad it worked out! Did you ever figure out what caused it?

What version of Unity are you using, and does the same issue happen in a new project?

You have to connect the alpha channel to either Opacity or Opacity clip to make this work. If you want to get as close to Unity's sprites as possible, start with the 2D/Sprite preset in SF, and then hook it up the way you want it to be.

Keep in mind that transparency is in the alpha channel, so in this case the transparency isn't applied at all. You'll need to blend based on the alpha channel. The common case is to use a lerp node, with the background in A and the foreground in B, with the foreground alpha channel in the T input of the lerp node.

Shaders can't set the values of shader properties, so this is impossible I'm afraid

Hey! It is, though very very slowly at this point, due to other projects having priority, which makes me put emphasis on bugfixing rather than adding features. That being said, Shader Forge includes source now, so it's possible to extend it in the meantime if you want to

It looks like you're on an old version of SF, it shouldn't happen with the latest

I'd try restarting Unity between step 3 and 4! The .dll might still be loaded