I use a hkc control panel and it's rf stuff
Then my ha platform is home assistant. I then link my alarm to my ha with an esp 32 module, flashed with esp home
The "guard response" is a lie aswell as I seen one of these systems get set off and no guard was seen for over a hour its been going off they got a proper alarm system now
I change all batteries every 2 years.
Panasonic or duracell
meaningless see attached graph showing discharge curve. They run then once they start to drop are dead within 1 - 2 weeks
see above
Yes, as you say the device should poll every x seconds or minutes (depends on brand) some stuff can be hours!
Once it hasnt recieved them over period x then the panel reports supervision failure