Thanks Wildfire for trying to explain the water level issue.
Shank ; If your battery cells are a little low on water then YES fill to recommended Fill Line but if the plates inside it are exposed it is best to "just" cover them and then charge the battery to avoid a boil over.
True ; A fully charged battery is the best way to store it and it should not freeze because if it's that cold to freeze a fully charged battery you have bigger problems to worry about. LoL ! Also it is not good for the battery's life to be fully discharged repeatedly as it will cause a build up of Lead Sulfate on the plates. Needless to say never ever attempt to charge a frozen battery ! Most batteries come with a 5 year warranty so anything after that ? Everything has a lifespan but by doing preventive maintenance (clean it, fill it, charge it ) you can extend it's life. Also a good time to check the connecters. As for storing them on wood or rubber ? Mmmmmmm ? At the price of a new battery I will stick with the old scrap of wood because I'm old school and cheap.
As a disclaimer I am not a battery tech nor do I sell them.
Thanks Waverunner ! Good pic !