you could use these for straight switches
https://sonoff.tech/product/wifi-diy-smart-switches/sonoff-mini
but id change them into their other mode to keep privacy etc
look into home assistant to do it all yourself
The 3-2-1 backup strategy simply states that you should have 3 copies of your data (your production data and 2 backup copies) on two different media (disk and tape) with one copy off-site for disaster recovery.
granted tape isnt used much anymore but the principle remains, 3 copies of data 2 backups and at least 1 off site
backup left on site is one option, but its like sage, word etc its up to the client to backup unless they are paying for a managed backup solution off site etc. Also should the backup be encrypted if your taking it and its found inside the pc etc
thats not a wiring issue then, maybe programming, how are you testing it, ie what are you doing to cause a full alarm. What happened when you did the bell test?
Id say every 5 years is fine. Better to replace before panels report it to prevent damage but modern panels seem to do better with failed battery's than the old dumb stuff