For the import operation, if you have JMP 11 or newer then I would first open the file using the Excel Wizard so that you can avoid importing the top lines that contain the character data. That way the columns won't get turned into Character columns. Then you can take the Source script out of the resulting table and use that within your JSL script.
As far as saving goes, JMP will always save the column headers when saving as Excel. There is no option to avoid that. JMP doesn't really have a facility to use VBA or to drive other programs outside of JMP. It does have an Automation interface to be driven by other programs like VBA in Excel. You could write a VB program that drives both Excel and JMP and acts as a controller for the two of them, but that is getting more complicated. In that scenario, you could have JMP open the file, and then use VB/VBA to retrieve the data and again us VB/VBA to populate the data in the Excel table.
Brian Corcoran
JMP Development