According to a review from someone that has the same product. No it's not compatible. ): And the brand do no specify anything about those two products. I'm sorry.
The Q70R can connect to the SWA-8500S.
The rear box is connected wirelessly and the speakers are connected to the box by cable. The only thing you need is power.
The speakers are small and not very loud, so I use stands so they are closer to the ear. You can use 08-15 stands, just bear in mind that the speakers are small and the receiver also needs to be positioned (on a stand foot in my case).
Your soundbar already has Atmos speakers built in and is already Atmos capable. These speakers are only optional to improve the surround effect. Your soundbar only has a virtual surround mode, which means that the speakers in the back are simulated by the soundbar. You can improve the experience with these speakers. However, this has nothing to do with Atmos.
According to the manufacturer, a rear kit is not required for this, as you can connect additional speakers via W-Lan. Accordingly, we unfortunately cannot offer one.