There are no triggers as there is in SQL Server in Access.
The best way to do this is in the BeforeUpdate event of the form that the user is using to change a record. You can see what the user is changing, including the original value and the new value they are entering.
Yes if you want it to. You obviously have to put the relevant code into the event to make this happen such as a Docmd.RunSQL function or use ADO/DAO in the event to add a record. See help for the details