>Is there a tool, OCX, class, anything, that will allow the field order in a grid to be changed based on clicking on the column heading???

There have been a number of threads here on this, and it's certainly possible. You can automate the whole thing in grid/column/header classes, it's been a fairly major topic here on the UT. For a very simple case, you can just have something like this in your header Click:

set order to mytag
this.parent.parent.refresh

It depends on how much you're going to use it and how fancy you want to get, how much work to put into it...