We need to know more about the design of your database.
A "table" implies that you have multiple records--one record to each row of your table. If this is the case, a Summary field can be defined to compute and display a total for all records in your current found set or for a specific group of records in your found set.
To change the name of a field, you would open Manage | Database | Fields, find the field. Select it. Enter a new name and click change.
I can't quite picture the last question. You'll need to describe what you want in more detail.