That's about what I'd expect. The reminder beep starts quite soon, but it should run for 2-3 hours before the big red warning that blocks the screen...
Yes, the CS92A sends its updates too rarely (1 hour between updates if no changes have occurred) and does not send every message twice like the DTS92...
When I first got mine in 2015 it would run from batteries without complaining for about 3 hours and run another 3 hours complaining before it finally...
If the existing BDR relays are BDR91's then you can just clear the bindings on them and then bind them to your evohome, and depending on the model of...
No, it doesn't try to be clever and only operate one radiator for low demands. I have one zone with two radiators - one a long 2m radiator the other...