Arduino Synth Revisited

I've decided to revisit my Arduino synth project from last September in hopes of creating a versatile synthesizer shield. I'm rather partial to the digitally-controlled-analog approach. I had an XR2206 function generator IC lying about, so I decided to put it to work as a possible core/VCO of this endeavor. It's quite easy to set up for accurate sine wave generation though driving the frequency with a convenient voltage is still something I'm figuring out.
Datasheets always seem to get a little vague just in the real clutch areas I need to focus on - a circumstance I find myself in often when getting to know a component, I suppose I'm a bit impatient and would rather experiment than attempt to decipher datasheet specs which I'm unfamiliar with. - And of course, why not? - the experimentation is the fun part! As a kid I remember acquiring new transformer figures and excitedly attempting to morph them without consulting the highly visible photo-instructions printed on each package. It's efficient to approach a new situation with proper procedure dictated to you - but that always leave me asking, "Why is that the proper method? and is it really the best way?" more to come . . .