With any color transparency film, what you see is what you get after the film is processed. If you meter carefully and shoot in brilliant sunlight with lots of difference between the sun and shadows, the scene will be faithfully recorded with the high contrast just as it was. The highlights are easily blown out by overexposure if you dont meter carefully and take steps to prevent it.
If, on the other hand, the scene was hazy, or overcast, or foggy, the scene will be low in contrast compared to more standard lighting. Too, dull lighting conditions like overcast or fog will also cool the color considerably because such lighting contains much less warm, reddish light.
I believe that thinking in Zone System terms isnt really appropriate when using transparency films. You wont be able to adjust development to compensate for particular lighting and exposure as we might with with B&W negative films. The old adage, with transparency film, expose for the highlights and let the shadows fall where they may is pretty much the way it is.
If you set the exposure for a darker part of the scene, the highlights will be overexposed and look like someone applied bleach to them. Theyll be too light and lack both detail and color. Its a jarring effect that slide shooters learn to avoid.
A transparency looks best if the brightest parts of the scene are more or less correctly exposed. The darker areas look darker than you remember. In this way, the overall scene looks natural, even if somewhat darker overall than you recall.
The color you record is just how the slide will lookprovided your scene is lit with the type of light the film was intended for. Most transparency films are daylight balanced. That means that colors are recorded accurately in 5500K daylight or electronic flash. Both sources provide about the same color of light.
There is nothing that the lab (or you, if you do your own E6 processing) can do in the developing step to correct the color. For this reason, we use filters to match unusual light to expose the film to get natural looking color.
For example, the blue 80A, 80B, or 80C will help balance overly red sources like tungsten lights. Light blue cooling filters like the 82A, 82B, 82C can compensate for the overly red light when the sun is near the horizon and overly red. This can be particularly useful for portraits where red, orange, or yellow tinged faces are not wanted.
Likewise, the 81A, 81B, and 81C warming filters can greatly improve the color of transparency films when shot in cool light such as under overcast sky or in shade.
The first 5 categories of filters listed here along with polarizers, UV, and skylight filters are the most useful filters for using with transparency films. There are brief descriptions of the use of each that help explain how they improve color and the situations that are most appropriate for their use.
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Transparency film exposures need to be carefully metered because, unlike negative films, there is no latitude. We can exploit this to lighten or darken a scene within reason by fine-tuning the exposure. Some folks used to underexpose a scene considerably to simulate nighttime or to create a darker, gloomy scene for creative effects. Thats easily done with transparency films.
Youll get the best results with an incident meter or a reflected-light meter referenced to a gray card. You need to expose and keep a record to learn how a particular film responds. It has long been a standard practice for transparency shooters to test a film at the box speed and then alter it as needed to fine-tune the results.
For example, many transparency shooters find that the box speed gives them transparencies that are too light with unsatisfactory color saturation (not enough color intensity). By increasing the EI for the particular film, slightly darker, more saturated and satisfying transparencies result. It used to be common for users of Kodachrome 64 to expose the film at ASA 80, a 1/3rd-stop reduction from box speed, to give them the slightly darker, more saturated color they preferred. Of course, they still needed to mind the highlights so as not to overexpose them.
Fuji Velvia is a good E6 transparency film. Its subject to the same exposure constraints and color requirements that other transparency films are subject to.
Each film has its own color palette. Velvia has attracted many with its particular color rendition. Just as Kodachrome had a unique look that wasnt matched by other films, Fuji Velvia has its own unique look that many folks appreciate.
The last I saw, reversal printing materials for making color prints directly from transparencies and the special chemicals they require have all gone the way of the dodo, passenger pigeon and thylacine, at least in the US. I havent seen Ilfochrome for sale here since 2009. Even then, it had become too dear for most users. So its not likely that youll find a practical way to print it with a dichoric color enlarger.
If you want to make color darkroom prints, using C41 color negative films and printing them on RA4 paper is a much better choice.
I dont know the answer to What exactly is the range in stops of Velvia? More importantly, it is what it is and theres nothing we can do to alter it. You can discover the answer for yourself by actually shooting this film of a scene that youve metered and recorded the various light intensities. In this way youll have the answer.