Thanks a ton, CasMat. If I knew how to answer your Swampert question, I definately would to help you out, unfortunately, I think you're much more knowledgeable than I, so I doubt I have much to contribute.
But my guess would be that a Mixpert would make a better lead than a pure physical one, because it would be able to hit a wider spectrum of pokemon and also because it requires no setup (unlike a Cursepert). Beyond that, I really don't have any indepth analysis to give.
Also, for whether or not Stone Edge is needed on a Swampert Lead, well.. doesn't that simply depend on how many Gyarados leads you see? Nothing else comes to mind immediately for what Stone Edge would be needed for, so this would be up to your personal preference/experience. In my case, I probably wouldn't use Stone Edge because I see mostly Gengar, Weavile and Heracross leads.. pretty much nothing else.
Sorry if my "advice" is totally useless and obvious, just trying to help out. ;;>_>
Very useful in fact... Especially the insight on Stone Edge. (Of course I'll have to see if it is true for my area too)
I should tell you that checking the analysis on that pokemon is also useful for choosing EVs, because while what I typed is "generally" accurate, a good few pokemon have better spreads tailored to the individual.