Ask Unity support and see if they may help you out getting the discount back :)

Yes, it works in RGB too!
Desaturation is very easy. Just plug in a 0-1 slider into the Des input of a desaturate node, and whichever texture / color you want to desaturate into Col

Connect a slider to this for a desaturation slider: http://acegikmo.com/shaderforge/nodes/?search=Desa...
If you want to control contrast, you can do that using the remap range node:

It's not just the blend node - when specular is white, your diffuse term will go black, simply because a white spec means it's fully reflective

This should now have been fixed in 0.31, which is now released too :)
(I have to sleep soon, these hotfixes are taking my time)

There was a nasty bug in 0.29 which caused it to save property nodes even after deleting them, which causes all these issues when loading existing shaders. I can't seem to be able to reproduce the duplication error though, but I'm sure it's related to the copy/paste issues (Create some nodes, copy, paste, delete, copy something else, paste, to see the effect)

This has been fixed in 0.31 anyhow, I'll roll out 0.31 in a few minutes

This has now been fixed in Beta 0.30

0.29 is out now, anyhow, so, yeah, go nuts! Make mistakes and then undo!