decide whether you think it is important for you after gathering enough info. rule of thumb is if you don't use your equipment that often, then dry box/cabi is essential. read more, learn more and you'd know what to do.
Yes, bringing your camera out into the sun and clicking it actually keeps the mould away.
But I'm sure u'll have stagnant days, unless you're avid hobbist or a full time photographer.
The dry cabin is there to ensure your photography asset's safety during these "stagnant" days.