Is this checkbox showing a field in the underlying object ? Or do you want a checkbox to allow the user to select some of the records on the page ? Since SKUID already shows a checkbox (at least in "table" view) I assume it would be a checkbox related to a value in the underlying object/model.
so the first step would be to add the field to the object in Salesforce...when you do that you can set the default value to be "checked".
#1 This should happen out-of-the-box. The fact that it's not working is a bug and we've added it to the work queue.
#2 The user would be able to edit this as usual.
#3 You can build a toggle filter that turns a condition on and off that checks the value of that field. Here's a tutorial with info on building a filter (Step 8 specifically.)