I joined tour for 9 days to Europe except UK, I exchanged 800 euro for 1 person, I've only used 300 euro totally, with 3 meals excluded and some entrace fee for Museums and some tourist spots. Actually you don't have to exchange swiss france for Switzerland as most of the shops accept Euro as well. For buying expensive stuff, like Watches & handbags, I paid by credit card, but not suggest, because the exchange rate charged by the bank is not good, using cash would be cheaper.
For the weather, when I went there, it's 22 May, the weather is hot when sunny, just a little bit cool in morning and at night, Switzerland is coldest if you go to snow mountain like Mount Titlus, I have to wear down jacket.