You would have to look at the stand alone smoke alarms sell by date aswell
One bell will be in sab mode other bell I'm scb mode
scaMtronic only good for basic alarm , many systems have wireless though
Texecom
Hkc
Don't think the Vanderbilt will work for you if you need good wireless options
Keeping existing contacts and pirs , depends how well they are working but after 17uears why you want to keep them?