why should i trust you and the security of your pc with the private key of my wallet?
and:
http://btcbin.com/#dev does that delete only my entries?
Nothing is hosted on BTCBIN, all the data is stored on your device similar to the normal client. Altho the normal client has wallet encryption, this is ment to be just a wallet carrier.
And yes, it will all the wallets. But im think your confused still about how the app works.