What version of JMP are you using?
JMP 16 has expanded the ability to capture the details of table manipulation to the log. Prior to that, one had to write more JSL.
However, your step 1 is there, you just have to know where it is. After you have opened your Excel file, go to the Data table, and right click on the green triangle that is next to the word "Source" in the tables panel on the upper left side of the display. It contains the JSL required to import the Excel file.
Next, you can create the new columns interactively, and apply the formulas using the formula editor. Then if you right click on the the red triangle in the same Table Panel, you can select Copy Table Script. If you then open a new script window, and paste the copied table script into the window, you will see the JSL required to create those new columns and formulas.
Jim