Networking – popular application for Windows 7 to find nearby WiFi networks

Where there's a will there's a way ;)

From a stock iPhone this is not possible from the settings. The information that you want is stored in the iPhone's keychain. If you have access to the iPhone SDK you can start messing around if you like, but I will leave it at that since that would be a StackOverflow answer.

Exact location is: /private/var/Keychains/keychain-2.db

Not that I am aware, and if it were to work like that, it could be potentially very dangerous.

If I mis understood you, and you mean simply connect to whichever connection is strongest at any given moment from a pre defined list, again, this is not how it works.

Windows should automatically always connect to the strongest signal at the time it is turned on and will not switch until the connection is lost/very weak.

One of the easiest solutions I can think of is to quickly toggle wireless off/on when you want to switch but this is more of a workaround than a good solution.