When you create a filter, you choose which widgets the filter acts against. In that way, a filter can be as global or widget-specific as you configure it to be.
For your second point, it depends on what you mean. Many widgets support interactivity that can act against other widgets themselves, like a list that shows you a fuller details panel for the selected item. You could have a hierarchy, I suppose, where a selection in one widget shows items in a second, selection in the second shows items in a third, and so on.
- Josh Carlson
Kendall County GIS