Hi,
Blending animation is best done using animator, not easy to do with playmaker and also not easy to do in script.
But you can try.
For the idle to wait until ended when pressing a button you can try this:
state 1 : use 'Play animation' action and set a Finish Event to connect to state 2
state 2 : use 'bool test' and have a bool variable (call it "Button Pressed" for example)
if true go to state 3 , if false go back to state 1
You will also need to set the "Button Pressed" bool when the button is pressed.