6 years ago I changed to Kool Stop Salmons from stock pads on a canti bike and immediately found a significant increase in braking power/reduction of needed hand pressure.
The front pair lasted a good 4 seasons (fronts wear faster than the rears for me) , and while I keep my rims and pads clean, am not a brake dragger, they still lasted a really good long time, much longer than I expected.

re the clean rim/pad thing--in my experience, this is a big factor in keeping your braking to its best possible condition and stop it slowly deteriorating over time-- after a wet ride, right away wipe the grit off the rims with a dry cloth, and do the pads while youre at it, it takes only a minute to do.

re interrupter cross levers, they work well and if she has any concerns about not being comfortable with only drop levers, they are nice to have and I don't really see a downside to them. They are handy in lots of situations when on the tops.