Pet sensors are not best especially with cats changing height as they appear much taller to the sensor. How close to the sensor is the cat when it alarms.
Best bet in any pet environment is perimeter protection
Yes as above looks like a bus or device issue. Assuming you have checked and tested the cabling then just remove one device at a time. You could also split the busses as iirc the 96 has 2 busses
No it can't. Either run a cable to it or get a flashing led kit
I.e.
https://www.securitywarehouse.co.uk/catalog/bentley-double-flash-unit-with-two-leds-p-3742.html