Hi Clubho,
We recommend a minimum of about 6 inches from the ceiling because of the top-firing driver. You want to give it enough breathing space so it can generate reflections from the ceiling.
The QS8s or QS4s don't need to be aimed or angled, except perhaps in a room with vaulted or cathedral ceiling and unusually high mounting locations. I've never tried them in such a room, but if you take into account the reverberant nature of such rooms, in theory the QS8s shouldn't need to be angled towards the listener even there.
Regards,
