Ideally you might want to extract only post column as it will hold the value post all processing steps from Adobe Analytics.
Data feed is the raw data as it is being received and you will need to import it in a database and create queries to output what you want to see. If you want to ovoid this, Data Warehouse might be more suited for what you want to do.
There is also an options when you built a report in Adobe Analytics (not Analysis Workspace), to export data using "...more" >> Extract Data . Data Extracts can process a maximum number of 50,000 rows in a single request.