UML14 — Questions about CentralBufferNode semantic

I have a question about the flow semantic according to
a CentralBufferNode.

p.312 (Examples) says:
"...because each token can only be drawn from the object node
by one outgoing edge."

What exactly happens if a CentralBufferNode has more than one
outgoing edge. Is it defined which one is used?

In the example on p. 312 I cannot see why the edge leading to
the action "Use parts" is prefered to the action "Pack parts" as
described in the text ("All the parts that are not used will be packed...").

see above