Using the Sample superstore as a reference:
1) Let's plot a bar chart showing SUM(Quantity) for each Segment:
2) Right click on the x-axis (Segment):
Notice we don't have an option to edit the axis, only header. This is because only continous values form the AXIS.
3) Similarly, right click on the y-axis (Quantity):

Now we have the option to edit BOTH the axis and the header.
Reference:
2) Right click on the x-axis (Segment):
Notice we don't have an option to edit the axis, only header. This is because only continous values form the AXIS.
3) Similarly, right click on the y-axis (Quantity):

Now we have the option to edit BOTH the axis and the header.

The beauty of context filters is that according to Tableau's Order of Operations, they are executed before Sets.

This means that based on what Region's you've selected - Tableau will first only preserve the rows for those Regions. THEN, after this it will compute the Set , i.e , Bottom 10 products in each Region.
1) First let's create a set to compute the Bottom 10 Products by Profit.

2) Next, take region on the Rows Shelf followed by the Set we just created. Drag Region and the Set to the Filters Shelf as well.

3) Now, try to only visualize the data for the South Region:

4) The problem right now is that Tableau is computing the Set first (Bottom 10 Products), and then applying the Dimension Filter - South Region and hence these values are incorrect. Note how these aren't even 10 products, but rather just 8. To fix this, simply add Region to Context:

Upon doing this, we get the correct answer as :

References: https://help.tableau.com/current/pro/desktop/en-us/order_of_operations.htm
https://help.tableau.com/current/pro/desktop/en-us/filtering_context.htm

Explanation
For Standard Deviation and Variance, we don't need to use quick table calculations, since they are available by default. See below:

However, as seen in the types of quick table calculations available in Tableau, Rank and Moving Average belong to only this category.

Explanation
Measure names and values CANNOT be deleted in Tableau like other columns can. These are auto-generated.
Calculated Fields, and Number of records can both be deleted.

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.