First, you should not post 2 unrelated questions in one topic especially as one should be in a seperate part of the forum.
I cannot say anything about the first question.
For the second: To extend the PDS you cannot, directly. You have to create a new one with another name and more space, copy the members from the current PDS, delete the current PDS and rename the new PDS to the current name.
The problem I have is that people can explain things quickly but I can only comprehend slowly.