I have a very large dataset of manufacturing defect bin data.
My columns are the manufacturing batch IDs (called lots), and then each column is a defect bin, with the numeric value for that particular defect bin for each lot.
Does the column switcher do what you want? Here I created a pareto plot of a single variable in the big class sample data, then added the columns switcher using the icon indicated below to swap it out with any other column. Now clicking any column in the columns switcher list updates the plot.
For Item 2, I don't think you need to add the lot to the x grouping. You should be able to get what you want with just the data filter.