#1 ENTER NEW have the power to open a form on main stage or new_tab.
No, it has to be in a popup window
#2 EDIT & VIEW also have the capability to choose the output of the form (panel, new_tab, main).
EDIT has to be in a popup window. VIEW already supports output - if it is the last action in a process it is displayed in wherever the process is displayed
#3 Custom Button have the capability to choose the output of the form (panel, new_tab, main).
Custom buttons already support output