Shumway is implementing APIs as needed, not targeting a specific SWF version.
Shumway does not currently support click-to-play because it is not a real browser plugin. It hooks into Firefox's click-to-play mechanism to conditionally override the Flash plugin. This is a hack and will soon be replaced with "jsplugins", a Firefox feature that will allow browser plugins to be written in JS and run in an out-of-process sandbox: