Welcome to the Cove. To keep it simple, ensure through your change process that the Design History File, especially Risk Management File (RMF) , is maintained as changes occur. I am assuming you are post design release and in production and talking just about changes in a post production environment.
Terminology? Sure, call it a Change Request (CR) while it is assembled and in review. Maybe it becomes a Change Order (CO) after approval and is in implementation phase. Don't get hung up on names. Keep it simple and easy to navigate for users. Some mature (and large) orgs have multiple CR merge into a single CO
Initiator. It depends. Typically, product changes are initiated by the responsible Design Engineer but this may be a different person after production release. Component / material changes may have different specification owners. No matter who initiates, the process must ensure an overall product impact (including Regulatory Filing Decision-- owned by the Reg department) and DHF (including RMF) impact. Assurance personnel will own their documents that may also be subject to CR /CO process.
While not an explicit regulatory requirement, including a decision on "Is this a Design Change?", is often helpful. Your Org creates it's own Design Change definition. That Design Change decision (if Yes), would trigger a more rigorous change process vs. non Design Changes that would be more of an express lane. Test your Design Change definition with scenarios before approving and implementing. Some orgs have a Design Change plan that explicitly assess if Inputs, Outputs, V&V, and Transfer are impacted. That plan would define actions that must be closed during the CO phase (Implementation) after the CO is approved.
Approvers? Assuming a design change, Design, Mfg, Quality, Regulatory are typical. If claims / customer requirements are impacted, then Mktg is in the loop.
Work Flow. I am assuming you are working a paper based system and not connected to an eQMS with built in workflow. Typical change phases are: Initiation (desk work for the owner and functional experts like Reg Affairs on Filing Impact, a design change decision is made an all impacted documents are identified), Review, Approval, Implementation Phase where Actions (docs updated, supplier process validation, training on a revised Mfg procedure - just a a couple of task examples) and ultimately the CO is closed after all tasks complete.
Good Change work comes from connecting with your peers outside of filling out forms / entering data into the system Vet the change with your peers BEFORE putting pen to paper / fingers to keyboard.
HTH. Have fun.