I am aware of the [0/2] checkbox summary in parent heading, but how could one get the same going for [(total TODO)/(total DONE)] ?
Just put the
[/] cookie in the upper level heading and then this will be updated with
[(total DONE)/(total TODO)] each time you change the status of a subheading. For example:
** My heading [2/4] *** DONE bake cake CLOSED: [2015-05-17 Sun 13:24] *** DONE make tea CLOSED: [2015-05-17 Sun 13:24] *** TODO drink tea *** TODO eat cake
If the cookie is not up-to-date, move the cursor to the cookie and type
C-c C-c to update.
Side comment -- If you're exporting your task list to HTML, you might be interested by the dashboard of my theme Bigblow  (which I'll try to add into ReadTheOrg as well). There, you can easily see counts of items, and even highlight them.
See demo on https://www.youtube.com/watch?v=DnSGSiXYuOk.