In list view, you'd need to do some scripting to hide/reveal the added field. The simplest way for a newbie to do this is to create two layouts that are identical (use duplicate layout to create the second copy of the layout) and add that field to one of the two, then use a button to switch between the layouts in order to hide/reveal the extra field. Other buttons can be used to sort the records.
Or you can use Table View
This has those capabilities and more built in, you can click on column headers to sort and the modify button can add/remove columns. I don't personally recommend that approach even though it has these capabilities, because other aspects of table view tend to make it harder for the general user to use. I tend to use table view as a "developer only" view of the data where it is very helpful in resolving issues with the design of a database.