Hi Inix,
We've been to Geneva during our Switzerland trip last year. As far as I know, people visit the Alps all year round, and some activities like hiking are during the summer. So it is not just all skiing.
Skiing is not important to us, and it's not available in May. We could go during late April though. For skiing, I know that we can rent the boots and skis, and they have beginner courses there. But do we need to bring our ski pants, gloves, etc?
I don't really like to bring a lot of clothing. Last year, when we went to Jungfrajosh in late April, we only wear a jacket and jeans. Temperatures at 0 degrees are quite ok for my wife and me, unless it is windy.