Help choosing my Orbi!

Hello!,

I've previously used powerline adapters to extend my wifi, but after moving to a bigger flat I've now looked at how I can improve on it.

This led me to researching mesh networks and after reading many reviews Orbi seemed to come out on top. 

Now I'm set on the brand. I'm now wondering what setup would be best for my needs. 

It's a two bedroom flat. 

Downstairs (from the front of the house backwards) there is a reception room, staircase, then a kitchen/dining room area (where the current VM router is located), there's then a hallway that leads past a bathroom and then at the end there's another reception room that opens out onto the garden. Downstairs is 513 SQ FT in total.

Upstairs there is a bedroom (above the reception room), the stair case, second bedroom (above kitchen) and an ensuite. Upstairs is 364 SQ FT in total.

Total floor area is 877 SQ FT (not including the garden)

My plan was to purchase the NETGEAR Orbi Home Mesh WiFi System 3-Pack (RBK23)

With the router connected in the kitchen.
Then one satellite in the reception room at the back of the house where we watch Netflix but currently stops every 15 minutes. My hope is by having one here we can watch TV and then extend further back into the garden. I also have an old xbox360 which might be nice to have a wired connection too.
Then a second satellite directly above the router in the second bedroom where I have my PS4, providing me with a wired connection. 

I have a couple of questions:
Does this sound like the right system to be purchasing?
Would I be better off just having the RBK50? (one router and satellite)
Is having a satellite directly above the router on another floor too close?

Hoping that people with more knowledge than me might be able to help with my decision!

Cheers