3/ The parameters that can be configured with zigbee2mqtt
Min rep interval
5 (s)
Max rep interval
1800 (s)
Min rep change
50 (0,5C)
I think by having any smart setup , it can be used for room’s temperature control eg. with radiator valve like the good old MAX!
I have now a setup of reporting every 0,05C change. It’s quite good , but can be even better eg. report not only by 0,05 C change but every 30 secs instead of only 30 mins
4/ Battery vs. precision
Surely by increasing the reporting interval the battery drains faster.
Actually the CR2450 is about 550-650 mAh, however with a little hack (3d printed case expansion of the backside) 2xAA can be used to increase the lifetime without expecting frequent battery replacement (~ 2500mAh)
5/ Some weird behavior
Few sensors (5 out of 10) were fluctuated initially the measured temperature see picture:
That was observed for few days then I have remove from the zigbee network. few days later repaired them back to the zigbee and I was surprised the problem has disappeared. 
All are still fine after one week like the good ones since the beginning…
It’s hard to explain the reason of that situation, probably the sensor inside required a bit more time to be stable after the package is arrived. eg. a kind of humidity issue inside the case…
So finally I am happy so far with that cheap sensor especially because the reporting parameter can be adjusted according to the actual requirements.