Now for the active window tab - I think it's a good idea to keep the border of a window with floating windows active at all times - because only then you know to which window the floating windows belong. Maybe we should even introduce a third color state for this case, as it wouldn't work to well with FFM if it would be the same. In any case, I think floating windows should just behave like any other window - ie. they can be active.
I think you're forgetting that floating windows of inactive windows are automatically hidden. IAW, all floating windows currently on screen belong to the same currently active app/window.