All,
First of all, it is true that the help page does not yet describe the revised layout and functionality of the Paste dialog. We will catch up soon no doubt.
Similarly the Calc Guide doesn't yet describe the new dialog - I'm working on that.
The nice thing about the "Run immediately" checkbox is that if unticked, you can press one of the four shortcut buttons to see which combination of options on the right hand side of the dialog would apply if that short cut button was actioned "for real". In previous versions of the software I often wondered which combination of options was equivalent to each of the (three) preset buttons.
The default is for the "Run immediately" button to be checked (whenever you open the dialog), so that a click on a preset button is actioned immediately and the dialog is closed, which is what the experienced used would require.
Regards,
Steve