Two things of note here, if your panel is pulling over half an amp quiescent that seems quite high to me and also if your new battery is dropping to 12v under load I would suggest its not a good battery.
cqr used to have clear plastic & you could see them inside
I use to find them inside cables upto 1m or so, I reckon they crawled in, & each time one crawled in behind the they;d move up more ?
battery in sounder will last 2yrs or 20 yrs....
When you completely down-power It remembers the codes zone settings ect in the NVM. But it wont keep the clock going while its down powered, that will default to watchdog