Get the Imperial Assault Campaign module for Vassal from http://www.vassalengine.org/wiki/Module:Star_Wars:_Imperial_Assault
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You read the mission events when they happen, so when deployment points activate and deactivate is known to the rebels. Where exactly they are is hidden information. Where the active deployment points are approximately is revealed when each deployment points is used.
You do not explicitly need to but since you must deploy figures 1 at a time, the rebels will know the exact location once you put your first figure out (unless you are deploying a large figure)
And unless there is a figure on the deployment point already. Then the deployed figure is deployed as close to the deployment point as possible, and the actual space is somewhat obfuscated.