Gatha itself can be used as plugin inspector! but I welcome any suggestion here!
Regarding documentation, I will add both user docs and developer docs. I need to find some free time after stable release.
You can do this! I myself use Commander and add a Working Tag. It only used for the purpose you proposed.
The current version of Gatha can do this easily!
I think we cannot have both the plugin and its draft! There is no difference between a tiddler in plugin and the same plugin in draft! So, we cannot have both at the same time. That will be very confusing!
I prefer to keep production wiki separate from user wiki!
This is out of scope of Gatha! But I think @saqimtiaz had some nice idea here! I know there is some efforts on installing, updating plugins. @linonetwo has also some thoughts here.