Why can't you use an extension to create a CheckBox? There are few simple and good ones available on the Branch...
And for the second question: just use the HidePrefix variable:
Load * Inline
So the _p_org_id field (starts with '_') will not be visible in the Current Selections list.
I would recomment the variable extension. To be found at Qlik Branch
This extension allows you to create buttons, drop-down-lists, inputbox and slider.
If this helps you please mark this post as helpful or correct.