You can add reference lines, bands, distributions, or (in Tableau Desktop but not on the web) box plots to any continuous axis in the view.
Reference Lines - You can add a reference line at a constant or computed value on the axis. Computed values can be based on a specified field. You can also include confidence intervals with a reference line.

The only incorrect option is - It is mandatory to combine sheets when using Tableau.
All others are valid advantages that Dashboards provide when using Tableau!

Explanation
When you track data in Excel spreadsheets, you create them with the human interface in mind. To make your spreadsheets easy to read, you might include things like titles, stacked headers, notes, maybe empty rows and columns to add white space, and you probably have multiple tabs of data too.
When you want to analyze this data in Tableau, these aesthetically pleasing attributes make it very difficult for Tableau to interpret your data. That's where Data Interpreter can help.

Explanation
Yes, it is very much possible to use measures in the same view multiple times. For example, refer to the image below:

We are using BOTH the Sum of the revenue and the AVG of the revenue in the same view!