2 - Well, as long as there are just a few plugins, that page works, but imagine that the number of plugins increases significantly, it would be hard to update the page or find the plugin we are searching for. What I mean is a specific software for publishing and viewing plugins. :)
3 - Yes, but I'm talking about a possible new plugin's module which could add a button into the admin center, in the stats page, to get thing more organized, because that would be the only way the change the admin center (excluding the plugins page).
4 - It is possible to catch predefined events thrown by the Q2A core code, but I have find no way to throw them from plugins, not even from creating new ones in the Q2A source code, but I can also be missing something. :)