This is a simple thing, I think you would have found it by now if you have searched SCN for this...
1. Create a class implementing IF_WORKFLOW
2. Define a Event
3. In your workflow register this event as start event
4. Trigger this event on your action method
Standard workflows are for business processes, and I would suggest that you check with your WF consultant if a Workflow already exists for the process you are working on.
About the status, you should be able to get status from task id. There are some standard Functions available like this one "SAP_WAPI_WORKITEMS_BY_TASK". You really don't have to save it into a database.
Br,
Nadh
