Help with Optimum (Altice) Fiber and Router that cannot bridge

Hi Folks-

My ISP (Optimum) recently upgraded my house to Fiber lines.  The "Altice" modem/router combo cannot be bridged, according to Optimum tech support.  The label underneath says "FiberGateway GR240BG."  They claim that the bride feature is in the works, but not available yet.  They did leave me with a couple of "repeaters" but I still can't seem to get solid Wifi at all ends of my house.  My goal: use my existing Orbi RBR50 router + (2) RBS50's satellites OR any other system recommended in order to maximize wifi connection and speed throughout my house (3 floors, 5000 sq. ft with exterior Nest Cameras). 

So far, I have connected the Orbi router into the Altice router, set the Orbi to AP mode.  I changed the wifi settings within the Orbi AP settings screen to match the SSID and Password from the Altice Router.  Then I setup the two satellites - everything appears to be connected.  However, I am still getting poor internet speeds at the far end of the house - even though signal is strong to the satellites.  

1. Is this the best way to optimize my Wifi? Should I upgrade to a faster Orbi setup?

2. Should I simply ask for more "repeaters" from the ISP?

3. Theoretically, is there some loss of speed when connecting the Orbi Router to the Altice Router via CAT6?  I'm told I have 1 gbit fiber - but even standing next to the altice router i am only testing at around 200 down and 200 up.  and at the far end of the house, it's like 10 and 10.

Thoughts from the group?