Unpivot in Excel to get a flat list

Unpivot Table is designed to make a database list out of your
crosstab table. If you often analyze large datasets and prepare visual representations, Unpivot in Excel will become your tool. It also helps to modify the layout of your pivot table in order to create charts and graphs. It involves no coding or sophisticated formulas. Just several clicks for getting a reverse pivot list.

The only Microsoft tool that is capable of unpivoting is Power Query. However, it's built into Excel 2016 only. Though it can be downloaded to Excel 2013-2010, it works as a separate editor with many tabs that you'll have to go through and contains other unnecessary for unpivoting options. In addition, your data should be formatted as a table, and you'll need to manually select all your columns and confirm saving the result.

To unpivot in Excel, do the following:

1. Select any cell of your table and run Unpivot Table.
2. Adjust the selected data range if needed.
3. Check the option to separate data by a blank row if you want to.
4. Choose where to put the result: to a new worksheet or a workbook.
5. Click Unpivot.

See a more detailed description here.

No, transpose is a completely different operation. It simply converts rows into columns and vice versa.

No, depending on the options you select, the add-in will place the result either to a new worksheet or a new workbook. Your original table will remain intact.