G'day Phil,

The screen size is 62mm wide and 42mm high.  It is mounted by screws/nails/ or whatever fixings you choose, through the four mounting points around the edge of the screen.  The bluetooth transmission is from the screen.
I'm not sure what version of bluetooth it uses, its not listed in the manual or product specifications.  Realistically versions of bluetooth have no impact on a product like this - its only a factor to consider with things like high definition streaming for audio/visual quality. or if you're using a mobile phone 10 years old.

G'day Lloyd,

There isn't programming inside this Battery Monitor to do more than one battery at a time - if you want to keep track of each 3 individually, you'd need 3 x Battery Monitors.   There may be something on the market that can do exactly what you're after, but I dont know one off the top of my head other than something like an Electrodacus.

G'day Richard,

The installation manual states:

"This Battery Monitor is suitable for all common battery types including AGM, wet, gel, calcium and lithium."

Hope that helps.