Well, the Japanese do make Shochu out of sweet potatoes (and other things), so I guess wine and beer are not quite out of the question.
Yes. You can mash (as in enzymatically convert starches to sugars, not as in mashed-potatoes) any gourd (think pumpkin, squash, potatoes, sweet potatoes). They tend not to add too much noticeable flavor to a beer (just a general earthiness and some color contribution) so it's often recommended to oven roast them a little first to get some caramelization. Here is a recipe that uses sweet potatoes.
I sometimes use sweet potato for beer in a similar way as I do pumpkin. Just clean it up, shove it in the oven until it caramelizes a bit, mash it with a fork or whatever is at hand and add it to the mash - I usually use 1-2 kg (~2-4 lbs) for a 20L (5 gal?) batch. And from then on it's brewing as usual. Gives a nice colour to the beer though I can't say I've noticed any flavour.
Read about being able to mash them on their own, but I've yet to try that, not sure how I would go about it.
I would think it to be more of a mead ingredient.
Not quite the same but there’s a place in Denver that makes sweet potato vodka. So… I guess fermenting them works, which isn’t surprising. Since it is vodka it doesn’t really have a flavor of course.
Homebrewing - Beer, Mead, Wine, Cider
A community dedicated to homebrewing beer, mead, wine, cider and everything in between. If it ferments, bring it over here.
Share recipes, ideas, ask for feedback or just advice.
Some starting points for beginners:
Quick and diry guide to fermenting fruit - cider and wine