My understanding is that the level of disclosure depends on the circumstances. For small acquisitions by large companies, it's generally difficult to find information, especially for an asset purchase. For larger acquisitions (and other transactions) by US-listed public companies, if the threshold of materiality is met--usually around 5% of the pre-transaction market value of the acquirer--there will typically be public disclosure of the consideration paid, and sometimes further documentation such as fairness opinions, etc.

That said, the individual employees are typically subject to all kinds of agreements as part of the acquisition, including NDAs.