To maximize floor space and budget constraints and minimize visual clutter and wifely complaints, I'm considering using 5 Invisa HTR-7000 for L/C/R and Surrounds (complete timbre matching) plus 4 Invisa 600 as Atmos overhead speakers in a small area 5.1.4 setup. The area dimensions form a square of 12 feet (75" TV) by 12 feet; this area is the front corner of a much larger room (17 ft. x 36 ft. ); and my ceiling height is only 8 feet.

Questions:
1. Industry "wisdom" is to avoid 100% ceiling mounted installation for any Atmos application; does this also hold true for the HTR7000? If not, how has the HTR7000 overcome the technical limitations of an "all ceiling" 5.1.4 installation?
2. Given the downward firing angle of the HTR7000, how far back must I place my sofa's seating position from the plane of the LCR speakers?
3. Using Dolby's suggested angles for surround speakers (in an Atmos 5.1.4 setup), do I position the HTR7000 as if they were floor mounted surrounds just behind the plane of the seating position?

The HTR-7000 will produce a soundstage that will appear to be in front of the listener rather than localizing from above. With an 8’ ceiling, which does fall within the recommended height for Dolby Atmos, we recommend a mounting distance of 8-12’ from the listening position.
Rear channel application is the same recommended distance for optimal effect. Just like the front LCR, you need enough distance to create the psychoacoustic effect of a speaker at relative ear height. That and you will need some space to locate the Atmos height channels.
These recommendations are for optimal effect, short of it is, the system you are proposing is going to sound amazing, even if the space will not allow for an optimal set-up (most do not).

Mark Henninger reviewed a very similar system on the AVS forum you might find helpful: www.avsforum.com/goldenear-ultimate-invi...s-system-experience/

I'm looking into the HTR 7000 for a stereo application.
Is there any minimum distance from my front wall for the speakers to be installed or they can be installed right agains the wall (the closer it is from the wall the better will be the distance from speaker to listening position).

With the driver and tweeter directed away from the wall and toward your listening position, mounting the speakers in the ceiling just a couple inches in from the wall should be fine.

Same question, but what about with a 10 foot high ceiling?