According to Tableau's official documentation:

Explanation
A bullet graph is a variation of a bar graph developed to replace dashboard gauges and meters. A bullet graph is useful for comparing the performance of a primary measure to one or more other measures.
Therefore, we need at least 2 measures for creating bullet graphs.

Explanation
According to Tableau's order of operations, the Extract filter is right at the top of the hierarchy. The data filtered in the Extract is then passed on to what we see in the Data Pane. See below:

Explanation
Yes, it is possible to create worksheet-specific filters in Tableau.
When you add a filter to a worksheet, by default it applies to the current worksheet. Sometimes, however, you might want to apply the filter to other worksheets in the workbook.
Then, you can select specific worksheets to apply the filter to or apply it globally to all worksheets that use the same data source or related data sources.

Yes! It is possible to duplicate a field and add it to more than one hierarchy. Right click and choose duplicate.