contracting and expanding from high thermal changes is a possible issue, that could reduce its longevity.
when ni-cds leak it is usually very minor , they dont usually leak. they will collect some crud on the top around the vent (assuming it has a vent) and it usually doesnt even effect the connections.
they are more likly to leak or outgas when left charging or overcharged.
the thing is likly to store for a long time being ni-cd, and very unlikly to be a problem, even in the thermal changes, but eventually it will be less and less capacity and increase in self discharge and all just from time. so you might not want to store it for more than say 5 years, and when you get it out, you will want to cycle the battery a few times.
as usual a lot of that stuff is dependant on the quality of the build of the cell, so all i could possibly do is guess.
there ARE situation where a Built-In battery and its charging curcuit wont "Wake-Up" the battery after time, if you cant take it OUT of the device to ZAP it, you might want to cycle it every once in a while
