Hi Richard,
This discussion has been marked as "Best Answer" by the Original Poster. Your new question can be answered in this way:
No, there is no sort function at the bottom of a table.
There is a sort feature at the top of a column from a Header Row.
There is a sort feature for a table in Format Panel.
No, you can not sort one column by itself. Numbers mimics a database where each column is a "field" and each row is a "record".
After selecting a table, see the the options in the Format Panel > Sort.
More information on your main aim may lead to a solution.
Perhaps if you start a new discussion, it may attract more answers.
Regards,
Ian.