Ahh, damn.. I did write all that part as well, but dumped it cause you said you needed to know the network infrastructure.. Now I see, how come I didn´t quite understand that request 
Anyway..
I have three Rpi3B´s and a Odroid C2. Then i have an old Windows 2008 server and a VERY old QNAP NAS (TS-110).
One Rpi3 runing my main opehab setup. Another Rpi running an utility to IHC (IHC Captain), and the third Rpi runs a linux for browsing habpanel (my monitoring floorplan) only.
The Odriod C2 is running openhab as well. It´s a new setup (2.5M1) to test some Velbus devices I playing with.
My windows server is actually a WHS2011, but I only use it for mail server, (Hmailserver) and then I have Grafafa running for rendering charts for my main openhab server. My QNAP NAS is hardly ever used. It´s mainly file storage.
Regarding the BT.. I´m not sure I have an BT dongle. I kinda hoped I could use the Rpi for this. It´s place right next to the SMA inverter anyway, (aprox 50cm). I can buy a BT dongle if it´s needed.