As far as winglets are concerned, I believe you are referring to what are called endplates in terms of cars. There is a good example on Mulsanne's Corner and I have uploaded an image of one of the wings I designed (it has something similar to a NACA 4412 airfoil flipped upside down) and there end plates on it although they are built into the mounts. imgur. com/a/PhFcd (I don't have enough posts to post links yet).
I am having a hard time understanding what you are getting at with the wavy corners. Is there any way you could sketch something out so I could get a better idea. I'm not really knowledgeable enough to understand the acoustic side of aerodynamics. I've never really looked into it.