They are summaries and they are "not estimations." The answer pointed out there may be things missing from the data and also correctly pointed out that those numbers are usually summaries of the available data. An estimate is a different thing entirely.

@Luke makes a good point, because average volume can be deceptive since it will spike on most recent interest and market cap may be another useful liquidity metric

@siegel to clarify, the meaning is that you can get shares of most hard-to-borrows in your network, if you have a vendor relationship with a party who has shares

Maybe you could invent another label like "quantitative investment strategies" or "rules based investing" as a subset of active management. It sounds like the material is challenging you to think about nomenclature and taxonomy within a field and whether it maps what you see as reality. I don't want to interfere with that process by giving the answer I'm pretty sure a finance exam grader expects. You're probably better off taking courses in the philosophy department anyway. But I think you're on track for aligning with the SEC's definitions as regards ETFs, so that's useful.

It's not hard to provide the leverage, but all leverage is risky. If your upstart broker can't do it then you pay a fee and backup to a bigger broker with the facility. They might also require that they have oversight and run some risk checks on your book. When you get the credit you negotiate lower fees or you do it yourself. Then the CHF/all comes unhinged and you're down the tubes, while you're big brother banker is explaining to shareholders why they didn't see your blow-up coming.

Another vote for Halmos.

Probably a better question for money.stackexchange. IBD publishes data feeds and you can get it on the IBD website.

It's a short answer, but it's particularly useful for modelling. Something about OP's background tells me it's not what he's looking for, because it's so obvious and probably one of the first things that occurred to him.

It depends on your strategy, market conditions, and how well the algo choice overcomes gaming by other bots. No one is in a position to estimate the value of that for you, but if you'll send me all of your strategy code and a large retainer then I'll put a finer point on things :)