The cables are probably under the floorboards. Mice like to chew cables. The alarm is only low voltage so no issue apart from the one you have. But if it's been chewing mains cables too you have a bigger worry
its a chase to to the bottom but you need to worry about stuff, those that dont will be gone, those that do will be affected by those that dont. ive seen a rise in digi air being the same as red gsm apparently
no i dont id always default so see no need