FlightpathOBN,
Can you provide references / links to the research you cite? All of the explanations I have ever read refer o the winglet interacting with the tip vortex in a manner that reduces the strength of the vortex and thus reduces induced drag. Certainly, the toe-angle has an efect on the production of a small amount of thrust force that is not there when the winglet is present.
As for where the vortices come from, the explanation I gave regarding higher pressure above the wing and lower pressure underneath is correct. However, I simplified it by stating that the vortex appears at the wingtip. The reality is that many small vortices form along the length of the trailing edge but they all add up very shortly afterwards and eventually form a large tip vortex. This vortex will form wherever there is an "edge", such as the wingtip and the edge of the flaps (if they are deployed). Clearly the nature of the vortex sheet will change as he wing shape changes due to flap/slat deployment.
Lastly, I am intrigued by the laminar flow argument. It makes sense that lifting the vortex away from the wing tip to the tip of the winglet would keep the vortex flow away from the wing upper surface near the tip, which would, as you say, permit laminar flow to persist over a slightly larger area of the wing. Are you saying that the entire drag reduction from the winglet is due to this effect?