Well, they generally shoot on 35mm, then scan at low res to do the "offline edit," then when they have the final film all cut, they go back to the original negatives, and they scan only the footage that made it into the final film at 4k (which resolves to something around 3k, I think) to prepare for the "online edit," where effects and color correction are done. And, actually, if it's got a really big budget (like 80%) of the movies you see in theaters these days) they will do a "film-out" after they color correct/do all the effects on the 4k-scanned final cut. Finally, when all is done and the final cut with sound and everything is done, they use a film recorder (a very expensive machine that generally uses lasers or RGB lights to burn the high res digital image onto the print stock. Distributing in a digital medium is obviously much cheaper, but a lot of theaters are still lagging on digital projectors, so film-out is often the way to go if you want to reach a wide audience.
The 14-stop business does refer to the dynamic range (again, thank you for your corrections) of the actual stock that your shoot on. Like I said, you can kind of think of the color correction stage as "selecting" how much or how little you want out of that range, but it depends on how much you're paying for your online scans.
Agreed, it is better to just shoot away and see what you get, but I guess I just want to be able to zone out specific stocks accurately... that would definitely take some testing of individual stocks though, and I'm not sure how to go about measuring. It's all about composition and subject matter I suppose, but I get a strange masochistic pleasure from technical immersion-- the tools do not make the artist, but if an artist understands his tools, he'll be able to use them much more effectively.
Portra line has lower contrast thus a bit more dynamic range than Ektar. Portra 400 may have a bit more than Portra 160. However, even Ektar has very much for all practical purposes, don't listen to internet legends that "you must nail down the exposure with Ektar like slide films", that is 100% bullshit.
So, it would go Portra 400 > Portra 160 > Ektar for the Kodak line, I suppose. But in any case, I would select the product on other criteria because all of them provide enough dynamic range to suit practically all purposes.
EDIT: Let me preface this with "I'm an amateur here, but ...."
I would personally classify Ektar as a narrow latitude film. The image will display if under or overexposed, but the side effects show the quality diminishes even though individual details remain (read: the colors go off, and quickly).
So while I like it for now, I consider it very narrow. I have heard good things about Portra and under/over exposure there.
I do not like Reala, as the latitude is almost nonexstent IMO when exposed according to the light meter. You get the narrow window of correct lighting, pitch black shadows with no definition, and blown out highlights, all in the same picture. It boggles the mind.
I'm personally working my way up to testing more film types. I picked up a roll of Kodak UC 400, and after that it's off to Portra 400 to test. That's about all I can really suggest now: Get single rolls here and there, and just shoot them! Make notes after you get them developed and tally a list of what films you liked and disliked.