How much can ball handler use his arm?

[potato]

If the ball handler has the rights to the vertical space above the player, is it illegal for him to use the hand to block/push the defender's hand/arm away should the defender extend his arm into the handler's vertical space during layup, assuming the ball handler's arm remains within his vertical space and not extended into the defender's vertical space.

Also for a defender trying to block a standing still handler trying to pass the ball, is it illegal for the defender to extend his arms position towards the handler to restrict the handler's arm movement (close but no contact was made however the handler won't be able to make a pass/turn/swing his arms without coming in contact with the defender's arm/chest and even so his movement would be restricted). Would you call it impeding of movement on the defense when the handler arms comes into contact with the defender and arm movement restricted?