Explanation
The computer on which you are installing or upgrading Tableau Server must meet the minimum hardware requirements. If the Setup program determines that your computer does not meet the following requirements, you will not be able to install Tableau Server.
These minimum requirements are appropriate for a computer that you use for prototyping and testing of Tableau Server. They apply to single-node installations and to each computer in a distributed installation.

Explanation
By default, all of the above mentioned are stored in Documents -> My Tableau Repository

Explanation
From the data pane, simply right click on the dimension, choose geographic role, and then select the appropriate role as follows:

Explanation
Of course! Follow along:
Right click on any measure, and choose Discrete as shown:

Once you do this, the green pill becomes blue in colour, indicating that it is now Discrete!

Explanation
The following is the official documentation for the String function LEFT: