and most of the rest should come very soon.
What is important to understand is MyMenus provides a platform on which to build menus, each item in a menu can be wikitext macros etc... that you can place in any tiddler.
If you can do it in wikitext you can do it in a menu item
So for example if you install a breadcrumbs plugin and know how to toggle it on and off in wiki-text you can make it a menu item to do so.
There is however a lot that can be done even with native tiddlywiki, such as toggling system tags, from view templates to alternate Stylesheets.
I expect we can quickly build a list of shareable menus that do much of what you ask above, and where they must we can indicate they have a dependency on another macro or plugin.
People with the knowledge and experience to do so, can contribute menus that manipulate the elements that you ask for, to customize your TW's,
I hope the library of menus we build will meet all your needs. I will add these to the requirements.
Regards
Tony