Equipment question RBK53S Plus addition Satellites

[LICNYC]

Hello,

I am looking to add to ORBI system to my home and yard. I live in a 100 plus year old 4 story brick building. I am looking to start with the RBK53S (Router and 2 Satellites) system. I would also like to add the RBS50 to my basement and the RBS50Y to my yard. I have run Cat6 cables from the router location to each of the 3 inside satellite locations, for a backhaul. Will these 3 units work together? I read you can have 3 satellites on that model router, but I am not sure if the yard unit counts as one satellites? 

Also, I have two additional Cat6 runs that currently have apple express units for music playing devices. If I connect these to the router, through a gig switch, do I need to configure them in a certain way. I read several replies on this subject but never with this exact setup.

Thank you in advance for any help you can provide. 

[FURRYe38]

Some users have reported having 6 to 9 RBS connected to one RBR. 

https://kb.netgear.com/000051205/What-is-Ethernet-backhaul-and-how-do-I-set-it-up-on-my-Orbi-WiFi-Sy...

What is the distance between the router and satellite(s)? 30 feet is recommended in between RBR and RBS to begin with depending upon building materials when wirelessly connected. https://kb.netgear.com/000036466/How-far-should-I-place-my-Orbi-satellite-from-my-Orbi-router 

Brick maybe a factor in getting good coverage.