I believe the idea is nobody would willingly sign a contract that does nothing to benefit themselves so they must have been mislead into the agreement thus it is invalid. Sort of a rational actor theory of law.
Typically yes, access to the information is the proper consideration for agreeing not to further disclose the information. But as lisper says [0], that will also typically be spelled out in the contract.
If a contract doesn't outline consideration, and the jurisdiction requires consideration, then the lawyer writing the contract was not very good at their job...
Possibly. But the contract doesn't say so. This is exactly why the consideration has to be explicit, so the judge adjudicating disputes doesn't have to guess about such things.
