But what you don't get with an index (at least, I don't think you do? I admit my ignorance on this) is the sort of transparency and ability to dig deep into the algorithm(s) that it appears you'd get with something like Quantopian. And possibly the ability to tweak that algorithm. Basically, a market for starter Quantopian algorithms that are more advanced than the samples on the site - I think that's vastly different than an index, and I could see paying for something like that.
Sure you do. All index funds disclose their holdings, and index ETFs show their constituent equities, along with any tracking error from the index being tracked. A long time ago, "proprietary" traders would perform index arbitrage in this fashion.
