1. You are correct. For both filters, you can apply them to multiple worksheets. With quick filters, you can show the filters on a dashboard or in a worksheet and change your view based on the selections made on the filters. Quick filters can be built off dimensions and measures. Action filters on the other hand are applied through actions made on the dashboard (selecting or clicking on a view). These action filters can highlight, show menu options, or exclude values like quick filters do.
2. The filter pane allows you to do additional changes to action filters (adding them to context for instance).
Hope this helps!