not sure what you’re trying to do and I can’t answer about FW7 caching, but if you’re having troubles with the browser loading an outdated external resource, like a css or js file, this is what I’m usually doing:
I’m simply adding a version to the filename. For example <link href="style.css"> will load the cached file in almost any browser, <link href="style.css?v=1> will reload the file once. If you add a timestamp (for example), your file will never be cached.