it depends on risk, building type etc. Id say as a minimum all external doors and double detection ground floor areas. Then trap protection corridors etc
fss means nothing. How many times have you had Signal but can't make a call. If the signal is important use something that polls and ensures the path is actually there.
No one can know all about all brands, I'd say a company can train and support a few well, all less so. Specialise in a few, train and know the products well. Much like cars you wouldn't take your merc to Hyundai garage
assuming its a 50131 system and certificated to g2 then it should of been setup for daily test calls. I'm also assuming you pay your monitoring and maintenance to your installer not the arc?