What maintenance does the housing require ?
There is no need to apply a special lotion or other chemical agent to the housing in regular intervals (on the contrary, this could cause damage, depending on its chemical properties!) After use in salt water, all that has to be done, is to rinse the housing in clear, fresh water at the end of the day. After returning home at the end of your holiday, a drop of regular machine oil onto the screws of the closing rail can be recommended. As you know, salt water is very aggressive for any material: so just rinse it off and dry the housing. That's all.
Do not expose the housing to direct sunlight for extended periods of time. A greenhouse effect will develop inside the housing and that is something that will do neither your camera, nor your film or housing any good. Cover it with you towel.
With regards to long term storage, keep the housing in a dark, dry place and do not flatten it by putting other things on top of the housing. Folds in the material, and /or extreme fluctuations of temperature together with the factor time can start microscopic cracks forming in the foil. So, store its loosely and put a piece of foam into the opening to allow the air to circulate.