According to this site, helium dissolves into water. Would there be enough to elicit a voice change? What else besides helium could I dissolve into a drink and alter a voice? (Nothing hazardous to my health, of course)
Finally, how would I go about performing the dissolving process?
Even if you could dissolve a significant amount of helium in a drink, it’s going to come out of your stomach, not your lungs. So it’s not going to pass through the vocal cords on its way out. It changes the sound of your burp, but not your voice.
True, unless you breathe the helium out of the beverage into your lungs.
Also, is it possible for a beverage to coat the vocal chords and alter your voice?
Only if you inhale it (not recommended). The vocal chords are down in the windpipe, not somewhere that a beverage normally reaches (diagram). I’m not sure how drinking water/lemon juice really helps in singing, except by moistening the back of the throat and probably increasing the humidity (thus perhaps moistening the windpipe).