Hi Chris,
Sorry if this is a little long!
Firstly, I finally found a page on the Yamaha website that confirms that Tyros 2-5 keyboards are compatible with the MB-BT1 and the UD-BT01. See
https://au.yamaha.com/files/download/other_assets/6/789396/UD-BT01_MD-BT01_Compatible_Apps_and_Products_List_161003.pdfAs a preamble, for some years I have been using an Excel Spreadsheet to open the required song's PDF file and to set my Tyros 4's registration to the correct one. (Each Registration is sequentially numbered in my case as in Bank Number, Registration Bank number. I use the Sendmidi.exe utility to actually change registrations from within my Excel macros).
I am now using MobileSheets to do much the same thing by using the Patch Change midi command.
I intend to use my new UB-BT01 to send the same commands via Bluetooth from both my Nexus 9 tablet an Surface Book 2. Hopefully it will arrive from Perth tomorrow (1000km to the South) and I will then report the results to this thread.
As to the Surface Book 2, I can use it and the USB ports as you suggest with the screen reversed, but it feels a little heavy and bouncy on the Tyros' music stand. The screen alone rests nicely on the Tyro's display, and being closer, is perfect to read two side by side music pages in MobileSheets....
I also live in hope that MobileSheets Windows 10 might one day be able to play midi files directly on my keyboard, but I understand that there are some significant programming hurdles to overcome first.
Hopefully more to come tomorrow!
Cheers
John