Manage | Security is the area to investigate for each of these issues. As an example, we have receipts that when their status field changes to "printed" they may no longer be edited by data entry users with the privilege set assigned to their accounts. Only uses with a different privilege set--form managers, are allowed to change the data in such a record.
And Such security settings can also control the level of access for a given user for each layout and table in your database.
See "Editing record access privileges" in FileMaker Help and check out this particular sub section: "Entering a formula for limiting access on a record-by-record basis" for a description of how to set this up.