TL;DR - I have not seen any standards. Different QVWs would have to be made to suit different viewports/devices.
We went through the same thought process as yours and did not learn of any standard, perhaps because the topic is subjective. We read communities posts about zooming, implemented them, and tried various prototypes before fixing a resolution to target.
Dashboards do not output a fluid design. If we were to design a dashboard on a 19" monitor with 1280x960 pixel, executives with 24" monitor and 1920x1200 pixel resolution will see a significant amount of white space. They can zoom, but that may not necessarily fill up their entire screen appropriately. Executives prefer to receive UX that do not require them to take any action, such as zoom, to view the data appropriately. Fit to zoom might be enforced when dashboards open, but that does not guaranty that the dashboards will look clean.
One method that has helped us is to research monitor sizes, resolutions, UX acceptance among the decision-makers, and kept in mind the type of monitors we were planning on buying in the future. It was safe to say that, for us, 24" monitors with 1920x1080 pixel resolution was the sweet spot and therefore we targetted and developed for that. Most important details were kept in the area that would be visible, without scrolling, on a 19" monitor with 1280x960 pixel resolution so that majority of users could make decisions based on the numbers that fit in their viewport.
Managers and supervisors using a 19" monitor benefited, to an extent, using zooming add-ins for Chrome to fit a large dashboard on their montiors.
To add a little more complexity, for executives that prefer monitors with touch screen, fonts would have to be made larger so that information is easy to click and filter. Larger fonts reduces the amount of information that can be displayed and leads the IT team to become more innovative with dashboard designs. We have observed that everyone looks at only a limited set of numbers on a regular basis and our aim is to display just that information in a dominant form. As long as that information was available with no or limited scrolling, users were relatively happy.
TVs - many dashboards appear on large TV screens and stay up all day. Some TVs may not fit the dashboard appropriately. Such dashboards are built so that the dynamic information fits cleanly on a TV.
Our company standard is to design for the smallest resolution in common use, which here is 1024 x 768. With that resolution, using the IE client or QlikView directly, you should not have to deal with scroll bars. Our tabs usually have selections and information on the top and left, allowing easy expansion of the main charts down and to the right on larger monitors.
Some companies favor auto zooming to fit your resolution. I'm against that approach because of the havok it can play with carefully chosen font sizes and pixel-perfect alignment. I find that when zoomed, things can often end up looking pretty ugly, sometimes to the point of compromising usability.
While not a monitor size standard specifically, I also try to keep fonts as large as practical for people with bad eyes. I try to use 14 point Arial for chart titles and the like, and 12 point Arial for most everything else. Sometimes I have to compromise and drop to 11 point or 10 point, but I try to stay away from 9 point and below. Also, most text is pure black on pure white, again in an attempt to improve readability, though I've not actually read any studies on what text is easiest to read.
As with QueueWeRavn, we do have a couple dashboards that appear on large TV screens, and designed those dashboards specifically to fit.
I'll add one more pointer here related to your iPad comment in particular - when we came out with our new browser-based strategy in QV10 SR2 we published a set of simple guidelines / recommendations to consider when designing apps for the iPad. That document can be found here.