I have done the emitter planes both ways. You can certainly make them in SU, but sometimes, especially for ones outside shining light in through windows, etc., you don't always know you're going to need one until you're in KT and do a test render.
In SU, you can name the material LightEmit[x], where X is the power of the light when it gets into KT. But adjusting the power after the fact is finicky. I think I only do this when I know I want a surface to be an emitter, but it's almost as easy to just make sure the surface doesn't share a material name with something else and assign it Diffuse Light in KT. Sometimes when you try and adjust this in KT, the light just winks out and becomes not a light. You can just reassign it to Diffuse Light again and it comes back on. Hard to explain and a bit of a bug I think.
Not sure about the image. Isn't BMP uncompressed? Odd they don't have the TIFF option and didn't even realize it till now. So, you taught me something too!