1) - Depends on the organisations approach to amendments. I personally ensure major changes are re approved by relevant signatories. Minor changes sent for information but I have a covering statement which explains the approach to version control

2) Manage in a similar way to protocol and list the changed and track changes for reference.

3) Depending on the nature of changes and relevant to workstream (DM/Stats) - get approval by relevant parties. If changes are significant and changes to actual data process or data it self (CRFs/eCRFs) they must be re approved also.

4) Depends on the CRO and delegation of duties. Presumably if producing the DMP you have been delegated by Sponsor to do this, so CRO may need to be made aware.