The cellpro will have a storage setting, a lot of chargers do. If they don't they tend to have a voltage charge cutoff. This should be set to about 70% capacity which corresponds to about 11v I think?
Re storage like I mentioned I am lucky to have an old cooker in the shed. It is good you are taking precautions but without wanting to make you paranoid there are many dangers tolerated around the domestic environment- law mowers and petrol, CO2 and fires, flammable furniture etc.
Personally I think a ceramic pot placed in a barrel of sand would be sufficient for storage and charging.
That reminds me I keep meaning to sacrifice a lipo just to see in person how fierce they burn!