It looks like on your second bemating that you are adding 50 to the "x" part of the coordinates and it should be on the "y" part if you want it to be above the rectangles. It would also be an idea to turn off snapping before running this, because depending on the zoom level Autocad will still try to snap to objects close to script coordinates (or you can use the "non" keyword before every set of coordinates).
You can add in as many columns as you like (other than text based commands that can be difficult) so you could add in a column before the dimensions and another in front of the text to change layers, you would then need to add another right at the start to set the layer for drawing the rectangles.
Run the "layer" command from the keyboard and make note of the sequence of keystrokes that you need to enter in order to change layers, including how many <enters> (blank spaces) you need to exit the command. --TIP-- as the script jumps between excel cells it also counts that as an <enter> so you might need to play with how many spaces you use. Try it and see how you get on.
I don't mind helping, but custom programming services is something else. If you get stuck then post a copy of the actual excel file you have tried, it will be easier to debug if I can see the formulas and not have to type them out again.
Good Luck