heat detector compatibility question with Radionics panel

["gjertsen" <gjertsen@xxxxxxxxxx>]

I have an old timey D8112 Radionics panel at my new house and want to
replace the original heat detectors and smoke detectors. I don't want
to
replace the security panel at this time given that it works OK.
Looking at the compatibility
charts for this (and the web site compatibility info at Bosch and
System Sensor)
I see that they list this info for smoke detectors but nothing about
compatibility
for heat detectors. Is it safe to assume that I won't have an issue
with
the heat dectectors from a particular vendor? (I have 7 2-wire heat
detectors and
a 4-wire smoke detector in one zone with a 12V line)
I suspect that is the case given that I currently have Edwards GS heat
detectors
installed. I'm leaning towards System Sensor detectors because it
appears to
be a challenge to find Bosch vendors online (and would use the same
vendor
for all the detectors).

I'd also like to add 3 smoke detectors (for bedrooms for a total of
11). Pubs indicate
that there is 10 detector limit for one zone with 2-wire alarms.
Not sure why a 4-wire was put on the
system for single smoke detector, but my reading indicates that I can
hook up more 4-wire alarms without
a limitation, so I wanted to confirm that adding 3 4-wire alarms hooked
up to the
original 4-wire would work fine (and allow me to have 11 detectors in
one zone).
I'd planned on letting someone else do this part, but having trouble
getting someone to
do the work without trying to sell me an upgraded Bosch/Radionics
security panel.

Thanks for any pointers.