I've had an epilator from Braun, now I have one from Philips, and I can say that they are fairly noisy... But I don't see why you would be embarrassed if someone hears any noice? There are all sorts of appliances that make noice, so it could be anything really...
It does hurt to rip out hairs, it's something you'll have to live with, but you'll get used to the sensation eventually... My advice is to do it fast, it's less time spent in pain. Doing it slowly isn't more efficient or anything.
My Philips one has a kind of "massage" attachment that is supposed to sort of diffuse the pain, but it doesn't really work IMO.