Hi Sia,
You can define as many property trees as you like. I am surprised, though, since you should have at least a property tree called standard and one called obsolete, which are part of standard EH&S. Please check in cusoizing, the standard tree may not be assigned to an spec type (obsolete tree shouldn't be assigned to any spec type).
With regard to the waste properties: You can include any EH&S property in any property tree, whatever you need. Again, this is done in customizing.
Regarding B) I'm afraid I don't understand what you mean.
Ralph