Two questions:

1. I have selected certain full rows from my spreadsheet, and now I wish to invert that selection (i.e. I now want to select all the rows I didn't select in my first selection). How do I do that?

2. I would like to sort the rows in a selection based on the last letter in a text string. Each row has a cell containing a 7-letter text string ending in either a W or an M. I need to sort by W and M. How could i do this?