Am I using Black Body Emission correctly?

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I’ve been experimenting with ways to give some multi colored lighting to a Blender fluid simulation using the water material. I made an effect I like but have a feeling I’m using the Black Body emission node in a way it wasn’t entirely designed for.

My water object is placed inside two light spheres that have inverted normals and Black Body emission nodes. To get the colors I want reflected onto the water, I have attached an RGB Color Spectrum node to the Black Body's texture input.

Question 1:
Is this a valid node set up? Or should I be using a Texture emission instead of a Black Body emission? I don’t want to use a image or pattern for the light - I just want access to additional, more flexible colors than the Black Body’s default temperature slider offers.

Question 2:
I found that when the light emitters were set to transparent (so they could be hidden in the scene) I had to add a slight roughness value to the water material in order for the lighting effects to become visible on that water object. This is not necessary when the light emitters have an opacity greater than 0. Is that normal / natural, or a bug?