Dave,
1) It takes about five minutes to take them off, remove the sole, and install the new one.
2) I know a few models of Korkers have a tool but its not required for the torrents. Sometimes the change can be a bit tricky and there is a slight learning curve to determine the easiest way to install the sole.
3) I haven't tried it, just the studded felt and the hiking sole (which i have waded in also)

Hope this helps,
Mike