Select/Unselect All toggle

I have two questions:

1. How can I have all the checkboxes checked by default? It appears I can only have one selected per each custom property at a time.

2. How can I add a a Select/Unselect All toggle checkbox to each custom property, so that if selected all the checkboxes in that custom property will be selected.

Please see image below for an example of I need:

question 1.
Current versions of CP only support a single default value for each field, which is appropriate for a select box but insufficient for checkboxes. We are moving this request on the top of the list.

question 2.
A (rather small) modification is required to module CPsearch. The next version of CP will likely have that feature.