Explanation
Tableau Data Extract (TDE) is a snapshot of the data that Tableau stores locally. Good for very large datasets of which we only need few fields. Performance is optimised because it queries its own database engine instead of the local data source.
When you create an extract of your data, you can reduce the total amount of data by using filters and configuring other limits. After you create an extract, you can refresh it with data from the original data. When refreshing the data, you have the option to either do a full refresh, which replaces all of the contents in the extract, or you can do an incremental refresh, which only adds rows that are new since the previous refresh.
Extracts are advantageous for several reasons:
1) Supports large data sets: You can create extracts that contain billions of rows of data.
2) Fast to create: If you're working with large data sets, creating and working with extracts can be faster than working with the original data.
3) Help improve performance: When you interact with views that use extract data sources, you generally experience better performance than when interacting with views based on connections to the original data.
4) Support additional functionality: Extracts allow you to take advantage of Tableau functionality that's not available or supported by the original data, such as the ability to compute Count Distinct.
5) Provide offline access to your data: Extracts allow you to save and work with the data locally when the original data is not available. For example, when you are traveling.

Explanation
For a manual sort, no matter how the data changes, the values will always stay in the sort order you kept stuff in.
From the official website:

Explanation
Follow along:
1) Drag Assortment and Year ID (choose Discrete Month) to Columns shelf, and Sales to the Columns Shelf.
For sales, click on the pill -> choose Quick Table calculation -> Year over Year growth.
The view should now look like:

It is clear that October with -55.3% had the lowest Year on Year growth.

Explanation
Upon clicking on a filter, we see the following options:

Clearly, Regex Match is not one of these options!

Explanation
The following are 2 correct ways to copy the worksheet visualisation as an image:

AND