I can't seem to find a way to have the inspector pane closed upon opening Whisk, something simple I'm missing?
Interesting! 
I just tested this and the Inspector wouldn't stay open when restarting Whisk.
This is on our list to fix. I personally find it annoying too!
I don't recall at the very moment, but I think there was some technical reason that had to do with the inspector placement/sizing preventing us from properly saving it. Part of the issue is that this is attached to the web view, which we don't have great control over. There might be other strategies we can try though.