auto down window control for passanger?

That would require another complete window switch module, for both the 2001-2007 models, and for the 2008 and newer models. There's a separate circuit board and switch that are added to the main window switch board, and it would need to be band-aided in to the passenger side of the board.

We had a Volvo S40 in Florida on our last trip there, and all four windows had both express up and down. I wonder if those switches are the same or similar as Ford's newer switches...

Adding that extra board to the existing window switch board would be a 10. It's fairly complicated, and the housing isn't designed to hold an extra board.

I think Ajax found an aftermarket module that added express up and down to both of his front windows.