Separating the texture samplers and the tex2D function is planned! It is a bit tricky though in terms of interaction design, as it might get confusing if there are a plethora of additional texture related nodes, and you don't know which one to use from the beginning. Having just one Texture2D, Texture3D and Cubemap node makes things easier, but, as you mention there, it's not a very good system for when you need to sample a single texture with different UV coords or MIP levels.

Edit:

This is now implemented in Alpha 0.14 :)

http://www.acegikmo.com/shaderforge/images/Misc/Animated/shaderforge_textureasset_uv.gif

Both are optional. Plug in a value like 5 or something, into the exp input :)

If you want to use displacement and get correct shading, you need to have a normal map that matches the displacement, which applies to the Fresnel node as well

Not much to do about that! It's simply how Displacement/Vertex Offset works. You have this issue in UDK as well. It does however cast real-time shadows, so enable that on your directional light, for at least some shading :)

This is now fixed in alpha 0.13 :)

This is now fixed in alpha 0.13 :)

You mentioned: "Before Lightmapping (knocked the diffuse colour on the unity shader to 50% grey)"
If you keep it at 100% white, the built-in and the SF lightmap should match :)

This is probably related to the whole issue with Unity multiplying all incoming light by two, which seems to work somewhat differently. So, this means, the SF one will look darker because SF doesn't multiply real-time lighting with two, but the built in one does, so they look different. However, the double lighting seems built into the lightmapping, so SF will get the double one. But if you set the built-in shader to 50% grey, it will cancel out the double light, thus making it darker than the SF shader with lightmapping applied.

It's a bit messy and inconsistent, I'll look into all of this :)

If you keep the built-in Unity lightmap Color at white, they will (should) look the same. (At least in my tests)

Vector 4 and Float (Value) Parameters are now both implemented in alpha 0.13 :)