I haven't looked at the audio generating capabilities of Vuo, but I assume all standard additive/subtractive synthesis options should be viable.
Only with the most basic stuff, and good luck with that.
I'm a Bidule user from way back, nodes and noodles all the way. Same audio concepts as Reaktor core, except NI/Reaktor's user base and library is vast. I love the noodles.
Anyway, my two cents, in response to the OP:
Step 1: decide on some visual parameters -- for example, luminance/brightness, hue, saturation, R,G,B, alpha, etc. Less headaches if you commit to normalized ranges -- 0 to 1 for all parameters.
Step 2: make some artistic decisions -- for example, what sound parameter does red control? Filter and shape the visual data -- produce good, usable data.
Step 3: set up something in the audio world to receive data from your visual parameters, probably translated to either MIDI or OSC. Both are versatile and powerful.
Go to step 2, repeat.
Let's say luminance to frequency:
Instead of frequency directly, let's translate to midi note#:
luminance * 127 would translate luminance to the full range of note numbers
luminance * 24 + 60 would translate to two octaves starting at middle C
Then there are many ways to "quantize" the data to play more meaningful/"musical" notes/combinations.
Besides frequency (or pitch or note number), there are a whole bunch of other audio parameters. For example, there's amplitude (velocity, volume), many shades of timbre (EQ stuff/filters, modulation, waveshaping/distortion), fading between sounds/audio files/samples, selecting some synthesizer preset, things like speed/rate (frequency, but for some other sound shaping thing), or other settings like "thickness", "sparseness", and so on and so forth.
To use an audio/modular synthesis term, I might try to think of luminance as a "modulator" for some parameter -- or more likely some set of audio parameters.
In my ListTools node set there is a Scale Point List node that can be used along with a Make Points Along Line to scale the outputs of the bins in a bit more custom fashion. If you set the range of the MPAL to for instance from 0.5 to 10 and use a quadratic out curve (I think), it should halve the output from the lowest bins, and multiply the output for the highest bins by 10. You might also be able to do this with the Scale List node when I think about it.
Here's another spectrum plug I made using a different approach. Unfortunately this is even less accurate, but it looks fun and is useful as a visualizer. Here I have the "Calculate Amplitude for Frequencies" set to "quadratic", which arranges the bin values decently enough that they can be processed in an even row (In the previous composition I spaced the bins exponentially). With the bins spaced linearly they can then be processed as scalable rectangle layers. If anyone knows a good way of taking the bins and then reprocessing them into more accurate data then please let me know.
This is a frequency spectrum I made for VJ use, particularly in Resolume. My aim was to make a spectrum that would be fun to watch mostly, rather than being super accurate. I think it makes a good base source and then you can add effects from there, ie colours, feedback etc.